refactor(core): improve monero typing

diff --git a/core/src/apps/monero/get_address.py b/core/src/apps/monero/get_address.py
index 99b3e83b..9ddd3969 100644
--- a/core/src/apps/monero/get_address.py
+++ b/core/src/apps/monero/get_address.py
@@ -27,7 +27,8 @@ async def get_address(msg: MoneroGetAddress, keychain: Keychain) -> MoneroAddres
     await paths.validate_path(keychain, address_n)
 
     creds = misc.get_creds(keychain, address_n, msg.network_type)
-    addr = creds.address
+    address = creds.address
+    assert address is not None
 
     have_subaddress = (
         account is not None and minor is not None and (account, minor) != (0, 0)
@@ -44,7 +45,7 @@ async def get_address(msg: MoneroGetAddress, keychain: Keychain) -> MoneroAddres
         assert payment_id is not None
         if len(payment_id) != 8:
             raise ValueError("Invalid payment ID length")
-        addr = addresses.encode_addr(
+        address = addresses.encode_addr(
             net_version(msg.network_type, False, True),
             crypto_helpers.encodepoint(creds.spend_key_public),
             crypto_helpers.encodepoint(creds.view_key_public),
@@ -59,7 +60,7 @@ async def get_address(msg: MoneroGetAddress, keychain: Keychain) -> MoneroAddres
             creds.view_key_private, creds.spend_key_public, account, minor
         )
 
-        addr = addresses.encode_addr(
+        address = addresses.encode_addr(
             net_version(msg.network_type, True, False),
             crypto_helpers.encodepoint(pub_spend),
             crypto_helpers.encodepoint(pub_view),
@@ -70,12 +71,12 @@ async def get_address(msg: MoneroGetAddress, keychain: Keychain) -> MoneroAddres
 
         coin = "XMR"
         await show_address(
-            addr,
+            address,
             subtitle=TR.address__coin_address_template.format(coin),
-            address_qr="monero:" + addr,
+            address_qr="monero:" + address,
             path=paths.address_n_to_str(address_n),
             account=paths.get_account_name(coin, msg.address_n, PATTERN, SLIP44_ID),
             chunkify=bool(msg.chunkify),
         )
 
-    return MoneroAddress(address=addr.encode())
+    return MoneroAddress(address=address.encode())
diff --git a/core/src/apps/monero/get_watch_only.py b/core/src/apps/monero/get_watch_only.py
index 322f05d0..49834160 100644
--- a/core/src/apps/monero/get_watch_only.py
+++ b/core/src/apps/monero/get_watch_only.py
@@ -22,6 +22,7 @@ async def get_watch_only(msg: MoneroGetWatchKey, keychain: Keychain) -> MoneroWa
 
     creds = misc.get_creds(keychain, msg.address_n, msg.network_type)
     address = creds.address
+    assert address is not None
     watch_key = crypto_helpers.encodeint(creds.view_key_private)
 
     return MoneroWatchKey(watch_key=watch_key, address=address.encode())
diff --git a/core/src/apps/monero/key_image_sync.py b/core/src/apps/monero/key_image_sync.py
index b107be98..3e663fc8 100644
--- a/core/src/apps/monero/key_image_sync.py
+++ b/core/src/apps/monero/key_image_sync.py
@@ -6,6 +6,9 @@ from apps.common.keychain import auto_keychain
 from apps.monero import layout
 
 if TYPE_CHECKING:
+    from buffer_types import AnyBytes
+
+    from trezor.crypto.hashlib import sha3_256
     from trezor.messages import (
         MoneroKeyImageExportInitAck,
         MoneroKeyImageExportInitRequest,
@@ -13,7 +16,7 @@ if TYPE_CHECKING:
         MoneroKeyImageSyncStepAck,
         MoneroKeyImageSyncStepRequest,
     )
-    from trezor.ui.layouts.common import ProgressLayout
+    from trezor.ui import ProgressLayout
 
     from apps.common.keychain import Keychain
 
@@ -56,13 +59,13 @@ class KeyImageSync:
     def __init__(self):
         from apps.monero.xmr import crypto_helpers
 
-        self.current_output = -1
-        self.num_outputs = 0
-        self.expected_hash = b""
-        self.enc_key = b""
+        self.current_output: int = -1
+        self.num_outputs: int = 0
+        self.expected_hash: AnyBytes = b""
+        self.enc_key: AnyBytes = b""
         self.creds: AccountCreds | None = None
         self.subaddresses = {}
-        self.hasher = crypto_helpers.get_keccak()
+        self.hasher: sha3_256 = crypto_helpers.get_keccak()
 
 
 async def _init_step(
@@ -137,7 +140,7 @@ def _sync_step(
         crypto.encodeint_into(buff_mv[64:], sig[0][1])
 
         # Encrypt with enc_key
-        nonce, ciph, _ = chacha_poly.encrypt(s.enc_key, buff)
+        nonce, ciph = chacha_poly.encrypt(s.enc_key, buff)
 
         kis.append(MoneroExportedKeyImage(iv=nonce, blob=ciph))
 
diff --git a/core/src/apps/monero/layout.py b/core/src/apps/monero/layout.py
index 8c79c2e7..48703315 100644
--- a/core/src/apps/monero/layout.py
+++ b/core/src/apps/monero/layout.py
@@ -13,6 +13,8 @@ DUMMY_PAYMENT_ID = b"\x00\x00\x00\x00\x00\x00\x00\x00"
 
 
 if TYPE_CHECKING:
+    from buffer_types import AnyBytes
+
     from trezor.enums import MoneroNetworkType
     from trezor.messages import MoneroTransactionData, MoneroTransactionDestinationEntry
 
@@ -117,7 +119,7 @@ async def require_confirm_transaction(
     change_idx = get_change_addr_idx(outputs, tsx_data.change_dts)
     payment_id = tsx_data.payment_id  # local_cache_attribute
 
-    if tsx_data.unlock_time != 0:
+    if tsx_data.unlock_time is not None and tsx_data.unlock_time != 0:
         await _require_confirm_unlock_time(tsx_data.unlock_time)
 
     for idx, dst in enumerate(outputs):
@@ -142,6 +144,7 @@ async def require_confirm_transaction(
     ):
         await _require_confirm_payment_id(payment_id)
 
+    assert tsx_data.fee is not None
     await _require_confirm_fee(tsx_data.fee)
     progress.step(state, 0)
 
@@ -149,7 +152,7 @@ async def require_confirm_transaction(
 async def _require_confirm_output(
     dst: MoneroTransactionDestinationEntry,
     network_type: MoneroNetworkType,
-    payment_id: bytes | None,
+    payment_id: AnyBytes | None,
     chunkify: bool,
 ) -> None:
     """
@@ -160,7 +163,14 @@ async def _require_confirm_output(
     from apps.monero.xmr.addresses import encode_addr
     from apps.monero.xmr.networks import net_version
 
-    version = net_version(network_type, dst.is_subaddress, payment_id is not None)
+    assert dst.addr is not None
+    assert dst.addr.spend_public_key is not None
+    assert dst.addr.view_public_key is not None
+    assert dst.amount is not None
+
+    version = net_version(
+        network_type, dst.is_subaddress or False, payment_id is not None
+    )
     addr = encode_addr(
         version, dst.addr.spend_public_key, dst.addr.view_public_key, payment_id
     )
@@ -173,7 +183,7 @@ async def _require_confirm_output(
     )
 
 
-async def _require_confirm_payment_id(payment_id: bytes) -> None:
+async def _require_confirm_payment_id(payment_id: AnyBytes) -> None:
     from trezor.ui.layouts import confirm_blob
 
     await confirm_blob(
diff --git a/core/src/apps/monero/live_refresh.py b/core/src/apps/monero/live_refresh.py
index eb43ad4e..e30a5f80 100644
--- a/core/src/apps/monero/live_refresh.py
+++ b/core/src/apps/monero/live_refresh.py
@@ -11,7 +11,7 @@ if TYPE_CHECKING:
         MoneroLiveRefreshStepAck,
         MoneroLiveRefreshStepRequest,
     )
-    from trezor.ui.layouts.common import ProgressLayout
+    from trezor.ui import ProgressLayout
 
     from apps.common.keychain import Keychain
 
diff --git a/core/src/apps/monero/misc.py b/core/src/apps/monero/misc.py
index d6af6cbc..b6122a16 100644
--- a/core/src/apps/monero/misc.py
+++ b/core/src/apps/monero/misc.py
@@ -1,6 +1,8 @@
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
+    from buffer_types import AnyBytes
+
     from trezor.enums import MoneroNetworkType
 
     from apps.common.keychain import Keychain
@@ -27,12 +29,13 @@ def get_creds(
 
 def compute_tx_key(
     spend_key_private: Scalar,
-    tx_prefix_hash: bytes,
-    salt: bytes,
+    tx_prefix_hash: AnyBytes,
+    salt: AnyBytes,
     rand_mult_num: Scalar,
 ) -> bytes:
     from apps.monero.xmr import crypto, crypto_helpers
 
+    tx_prefix_hash = bytes(tx_prefix_hash)
     rand_inp = crypto.sc_add_into(None, spend_key_private, rand_mult_num)
     passwd = crypto_helpers.keccak_2hash(
         crypto_helpers.encodeint(rand_inp) + tx_prefix_hash
@@ -42,13 +45,14 @@ def compute_tx_key(
 
 
 def compute_enc_key_host(
-    view_key_private: Scalar, tx_prefix_hash: bytes
+    view_key_private: Scalar, tx_prefix_hash: AnyBytes
 ) -> tuple[bytes, bytes]:
     from trezor.crypto import random
 
     from apps.monero.xmr import crypto_helpers
 
     salt = random.bytes(32)
+    tx_prefix_hash = bytes(tx_prefix_hash)
     passwd = crypto_helpers.keccak_2hash(
         crypto_helpers.encodeint(view_key_private) + tx_prefix_hash
     )
diff --git a/core/src/apps/monero/signing/offloading_keys.py b/core/src/apps/monero/signing/offloading_keys.py
index 252adf39..60cabdfe 100644
--- a/core/src/apps/monero/signing/offloading_keys.py
+++ b/core/src/apps/monero/signing/offloading_keys.py
@@ -4,6 +4,8 @@ from typing import TYPE_CHECKING
 from apps.monero.xmr.crypto_helpers import compute_hmac
 
 if TYPE_CHECKING:
+    from buffer_types import AnyBuffer, AnyBytes
+
     from trezor.messages import (
         MoneroTransactionDestinationEntry,
         MoneroTransactionSourceEntry,
@@ -17,11 +19,11 @@ _BUILD_KEY_BUFFER = bytearray(_SECRET_LENGTH + _DISCRIMINATOR_LENGTH + _INDEX_LE
 
 
 def _build_key(
-    secret: bytes,
-    discriminator: bytes,
+    secret: AnyBytes,
+    discriminator: AnyBytes,
     index: int | None = None,
-    out: bytes | None = None,
-) -> bytes:
+    out: AnyBuffer | None = None,
+) -> AnyBuffer:
     """
     Creates an unique-purpose key
     """
@@ -54,49 +56,49 @@ def _build_key(
     return crypto_helpers.keccak_2hash(key_buff, out)
 
 
-def hmac_key_txin(key_hmac: bytes, idx: int) -> bytes:
+def hmac_key_txin(key_hmac: AnyBytes, idx: int) -> AnyBuffer:
     """
     (TxSourceEntry[i] || tx.vin[i]) hmac key
     """
     return _build_key(key_hmac, b"txin", idx)
 
 
-def hmac_key_txin_comm(key_hmac: bytes, idx: int) -> bytes:
+def hmac_key_txin_comm(key_hmac: AnyBytes, idx: int) -> AnyBuffer:
     """
     pseudo_outputs[i] hmac key. Pedersen commitment for inputs.
     """
     return _build_key(key_hmac, b"txin-comm", idx)
 
 
-def _hmac_key_txdst(key_hmac: bytes, idx: int) -> bytes:
+def _hmac_key_txdst(key_hmac: AnyBytes, idx: int) -> AnyBuffer:
     """
     TxDestinationEntry[i] hmac key
     """
     return _build_key(key_hmac, b"txdest", idx)
 
 
-def _hmac_key_txout(key_hmac: bytes, idx: int) -> bytes:
+def _hmac_key_txout(key_hmac: AnyBytes, idx: int) -> AnyBuffer:
     """
     (TxDestinationEntry[i] || tx.vout[i]) hmac key
     """
     return _build_key(key_hmac, b"txout", idx)
 
 
-def enc_key_txin_alpha(key_enc: bytes, idx: int) -> bytes:
+def enc_key_txin_alpha(key_enc: AnyBytes, idx: int) -> AnyBuffer:
     """
     Chacha20Poly1305 encryption key for alpha[i] used in Pedersen commitment in pseudo_outs[i]
     """
     return _build_key(key_enc, b"txin-alpha", idx)
 
 
-def enc_key_spend(key_enc: bytes, idx: int) -> bytes:
+def enc_key_spend(key_enc: AnyBytes, idx: int) -> AnyBuffer:
     """
     Chacha20Poly1305 encryption key for alpha[i] used in Pedersen commitment in pseudo_outs[i]
     """
     return _build_key(key_enc, b"txin-spend", idx)
 
 
-def key_signature(master: bytes, idx: int, is_iv: bool = False) -> bytes:
+def key_signature(master: AnyBytes, idx: int, is_iv: bool = False) -> AnyBuffer:
     """
     Generates signature offloading related offloading keys
     """
@@ -104,7 +106,7 @@ def key_signature(master: bytes, idx: int, is_iv: bool = False) -> bytes:
 
 
 def gen_hmac_vini(
-    key: bytes, src_entr: MoneroTransactionSourceEntry, vini_bin: bytes, idx: int
+    key: AnyBytes, src_entr: MoneroTransactionSourceEntry, vini_bin: AnyBytes, idx: int
 ) -> bytes:
     """
     Computes hmac (TxSourceEntry[i] || tx.vin[i])
@@ -122,6 +124,10 @@ def gen_hmac_vini(
     kwriter = get_keccak_writer()
     real_outputs = src_entr.outputs
     real_additional = src_entr.real_out_additional_tx_keys
+
+    assert src_entr.real_output is not None
+    assert src_entr.real_output_in_tx_index is not None
+
     src_entr.outputs = [src_entr.outputs[src_entr.real_output]]
     if real_additional and len(real_additional) > 1:
         src_entr.real_out_additional_tx_keys = [
@@ -139,7 +145,10 @@ def gen_hmac_vini(
 
 
 def gen_hmac_vouti(
-    key: bytes, dst_entr: MoneroTransactionDestinationEntry, tx_out_bin: bytes, idx: int
+    key: AnyBytes,
+    dst_entr: MoneroTransactionDestinationEntry,
+    tx_out_bin: AnyBytes,
+    idx: int,
 ) -> bytes:
     """
     Generates HMAC for (TxDestinationEntry[i] || tx.vout[i])
@@ -158,7 +167,7 @@ def gen_hmac_vouti(
 
 
 def gen_hmac_tsxdest(
-    key: bytes, dst_entr: MoneroTransactionDestinationEntry, idx: int
+    key: AnyBytes, dst_entr: MoneroTransactionDestinationEntry, idx: int
 ) -> bytes:
     """
     Generates HMAC for TxDestinationEntry[i]
@@ -175,7 +184,7 @@ def gen_hmac_tsxdest(
     return hmac_tsxdest
 
 
-def get_ki_from_vini(vini_bin: bytes) -> bytes:
+def get_ki_from_vini(vini_bin: AnyBytes) -> bytes:
     """
     Returns key image from the TxinToKey, which is currently
     serialized as the last 32 bytes.
diff --git a/core/src/apps/monero/signing/state.py b/core/src/apps/monero/signing/state.py
index ad9e3bde..c9bd2bc8 100644
--- a/core/src/apps/monero/signing/state.py
+++ b/core/src/apps/monero/signing/state.py
@@ -1,12 +1,13 @@
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
+    from buffer_types import AnyBytes
+
     from trezor.messages import MoneroTransactionDestinationEntry
 
     from apps.monero.xmr.credentials import AccountCreds
-    from apps.monero.xmr.crypto import Point, Scalar
 
-    Subaddresses = dict[bytes, tuple[int, int]]
+    Subaddresses = dict[AnyBytes, tuple[int, int]]
 
 
 class State:
@@ -32,8 +33,8 @@ class State:
         self.creds: AccountCreds | None = None
 
         # HMAC/encryption keys used to protect offloaded data
-        self.key_hmac: bytes | None = None
-        self.key_enc: bytes | None = None
+        self.key_hmac: AnyBytes
+        self.key_enc: AnyBytes | None = None
 
         """
         Transaction keys
@@ -43,8 +44,8 @@ class State:
         - for subaddresses the `r` is commonly denoted as `s`, however it is still just a random number
         - the keys are used to derive the one time address and its keys (P = H(A*r)*G + B)
         """
-        self.tx_priv: Scalar | None = None
-        self.tx_pub: Point | None = None
+        self.tx_priv: crypto.Scalar
+        self.tx_pub: crypto.Point | None = None
 
         """
         In some cases when subaddresses are used we need more tx_keys
@@ -56,21 +57,21 @@ class State:
         self.client_version = 0
         self.hard_fork = 12
 
-        self.input_count: int | None = 0
+        self.input_count: int = 0
         self.output_count = 0
         self.progress_total = 0
         self.progress_cur = 0
 
-        self.output_change: "MoneroTransactionDestinationEntry" | None = None
-        self.fee: int | None = 0
+        self.output_change: MoneroTransactionDestinationEntry | None = None
+        self.fee: int = 0
         self.tx_type = 0
 
         # wallet sub-address major index
         self.account_idx: int | None = 0
 
         # contains additional tx keys if need_additional_tx_keys is True
-        self.additional_tx_private_keys: list[Scalar] = []
-        self.additional_tx_public_keys: list[bytes] | None = []
+        self.additional_tx_private_keys: list[crypto.Scalar] = []
+        self.additional_tx_public_keys: list[AnyBytes] | None = []
 
         # currently processed input/output index
         self.current_input_index = -1
@@ -84,11 +85,11 @@ class State:
         self.summary_outs_money: int | None = 0
 
         # output commitments
-        self.output_pk_commitments: list[bytes] | None = []
+        self.output_pk_commitments: list[AnyBytes] | None = []
 
         self.output_amounts: list[int] | None = []
         # output *range proof* masks. HP10+ makes them deterministic.
-        self.output_masks: list[Scalar] | None = []
+        self.output_masks: list[crypto.Scalar] | None = []
 
         # the range proofs are calculated in batches, this denotes the grouping
         self.rsig_grouping: list[int] | None = []
@@ -96,9 +97,9 @@ class State:
         self.rsig_offload: bool | None = False
 
         # sum of all inputs' pseudo out masks
-        self.sumpouts_alphas: Scalar = crypto.Scalar(0)
+        self.sumpouts_alphas: crypto.Scalar = crypto.Scalar(0)
         # sum of all output' pseudo out masks
-        self.sumout: Scalar = crypto.Scalar(0)
+        self.sumout: crypto.Scalar = crypto.Scalar(0)
 
         self.subaddresses: Subaddresses | None = {}
 
diff --git a/core/src/apps/monero/signing/step_01_init_transaction.py b/core/src/apps/monero/signing/step_01_init_transaction.py
index b4fa7422..6eda38fe 100644
--- a/core/src/apps/monero/signing/step_01_init_transaction.py
+++ b/core/src/apps/monero/signing/step_01_init_transaction.py
@@ -10,6 +10,7 @@ from apps.monero.xmr import crypto, crypto_helpers, monero
 if TYPE_CHECKING:
     from trezor.messages import (
         MoneroAccountPublicAddress,
+        MoneroNetworkType,
         MoneroTransactionData,
         MoneroTransactionDestinationEntry,
         MoneroTransactionInitAck,
@@ -23,7 +24,7 @@ if TYPE_CHECKING:
 async def init_transaction(
     state: State,
     address_n: list,
-    network_type: int,
+    network_type: MoneroNetworkType,
     tsx_data: MoneroTransactionData,
     keychain,
     progress: MoneroTransactionProgress,
@@ -46,16 +47,18 @@ async def init_transaction(
 
     state.fee = state.fee if state.fee > 0 else 0
     state.tx_priv = crypto.random_scalar()
+    assert state.tx_priv is not None
     state.tx_pub = crypto.scalarmult_base_into(None, state.tx_priv)
     mem_trace(1)
 
+    assert tsx_data.num_inputs is not None
     state.input_count = tsx_data.num_inputs
     state.output_count = len(outputs)
-    assert state.input_count is not None
     state.progress_total = 4 + 3 * state.input_count + state.output_count
     state.progress_cur = 0
 
     # Ask for confirmation
+    assert state.creds.network_type is not None
     await layout.require_confirm_transaction(
         state,
         tsx_data,
@@ -69,6 +72,7 @@ async def init_transaction(
 
     # Basic transaction parameters
     state.output_change = tsx_data.change_dts
+    assert tsx_data.fee is not None
     state.fee = tsx_data.fee
     state.account_idx = tsx_data.account
     state.last_step = state.STEP_INIT
@@ -85,6 +89,7 @@ async def init_transaction(
     if state.output_count < 2:
         raise signing.NotEnoughOutputsError("At least two outputs are required")
 
+    assert tsx_data.rsig_data is not None
     _check_rsig_data(state, tsx_data.rsig_data)
     _check_subaddresses(state, outputs)
 
@@ -94,6 +99,8 @@ async def init_transaction(
     gc.collect()
 
     # Iterative tx_prefix_hash hash computation
+    assert state.tx_prefix_hasher is not None
+    assert tsx_data.unlock_time is not None
     state.tx_prefix_hasher.uvarint(2)  # current Monero transaction format (RingCT = 2)
     state.tx_prefix_hasher.uvarint(tsx_data.unlock_time)
     state.tx_prefix_hasher.uvarint(state.input_count)  # ContainerType, size
diff --git a/core/src/apps/monero/xmr/addresses.py b/core/src/apps/monero/xmr/addresses.py
index d7679b83..fc167540 100644
--- a/core/src/apps/monero/xmr/addresses.py
+++ b/core/src/apps/monero/xmr/addresses.py
@@ -1,6 +1,8 @@
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
+    from buffer_types import AnyBytes
+
     from trezor.messages import (
         MoneroAccountPublicAddress,
         MoneroTransactionDestinationEntry,
@@ -8,14 +10,14 @@ if TYPE_CHECKING:
 
 
 def encode_addr(
-    version, spend_pub: bytes, view_pub: bytes, payment_id: bytes | None = None
+    version, spend_pub: AnyBytes, view_pub: AnyBytes, payment_id: AnyBytes | None = None
 ) -> str:
     """
     Builds Monero address from public keys
     """
     from trezor.crypto import monero as tcry
 
-    buf = spend_pub + view_pub
+    buf = bytes(spend_pub) + bytes(view_pub)
     if payment_id:
         buf += bytes(payment_id)
     return tcry.xmr_base58_addr_encode_check(ord(version), bytes(buf))
@@ -34,11 +36,14 @@ def classify_subaddresses(
     addr_set = set()
     for tx in tx_dests:
         addr = tx.addr  # local_cache_attribute
+        assert addr is not None
         if change_addr and addr_eq(change_addr, addr):
             continue
+        assert addr.spend_public_key is not None
+        assert addr.view_public_key is not None
         # addr_to_hash
         # Creates hashable address representation
-        addr_hashed = bytes(addr.spend_public_key + addr.view_public_key)
+        addr_hashed = bytes(addr.spend_public_key) + bytes(addr.view_public_key)
         if addr_hashed in addr_set:
             continue
         addr_set.add(addr_hashed)
@@ -67,8 +72,10 @@ def get_change_addr_idx(
     if change_dts is None:
         return None
 
+    assert change_dts.addr is not None
     change_idx = None
     for idx, dst in enumerate(outputs):
+        assert dst.addr is not None
         if (
             change_dts.amount
             and change_dts.amount == dst.amount
diff --git a/core/src/apps/monero/xmr/bulletproof.py b/core/src/apps/monero/xmr/bulletproof.py
index 6d5d4a51..455cc12f 100644
--- a/core/src/apps/monero/xmr/bulletproof.py
+++ b/core/src/apps/monero/xmr/bulletproof.py
@@ -8,6 +8,7 @@ from apps.monero.xmr import crypto, crypto_helpers
 from apps.monero.xmr.serialize.int_serialize import dump_uvarint_b_into
 
 if TYPE_CHECKING:
+    from buffer_types import AnyBuffer, AnyBytes
     from typing import Generic, Iterator, TypeVar
 
     from .serialize_messages.tx_rsig_bulletproof import BulletproofPlus
@@ -86,12 +87,15 @@ def _ensure_dst_key(dst: bytearray | None = None) -> bytearray:
 
 
 def memcpy(
-    dst: bytearray, dst_off: int, src: bytes, src_off: int, len: int
+    dst: bytearray,
+    dst_off: int,
+    src: AnyBytes,
+    src_off: int,
+    length: int,
 ) -> bytearray:
     from trezor.utils import memcpy as tmemcpy
 
-    if dst is not None:
-        tmemcpy(dst, dst_off, src, src_off, len)
+    tmemcpy(dst, dst_off, src, src_off, length)
     return dst
 
 
@@ -111,7 +115,7 @@ def _gc_iter(i: int) -> None:
         gc_collect()
 
 
-def _invert(dst: bytearray | None, x: bytes) -> bytearray:
+def _invert(dst: bytearray | None, x: AnyBytes) -> bytearray:
     dst = _ensure_dst_key(dst)
     decodeint_into_noreduce(_tmp_sc_1, x)
     sc_inv_into(_tmp_sc_2, _tmp_sc_1)
@@ -163,7 +167,7 @@ def _sc_gen(dst: bytearray | None = None) -> bytearray:
     return dst
 
 
-def _sc_add(dst: bytearray | None, a: bytes, b: bytes) -> bytearray:
+def _sc_add(dst: bytearray | None, a: AnyBytes, b: AnyBytes) -> bytearray:
     dst = _ensure_dst_key(dst)
     decodeint_into_noreduce(_tmp_sc_1, a)
     decodeint_into_noreduce(_tmp_sc_2, b)
@@ -174,8 +178,8 @@ def _sc_add(dst: bytearray | None, a: bytes, b: bytes) -> bytearray:
 
 def _sc_sub(
     dst: bytearray | None,
-    a: bytes | Scalar,
-    b: bytes | Scalar,
+    a: AnyBytes | Scalar,
+    b: AnyBytes | Scalar,
 ) -> bytearray:
 
     dst = _ensure_dst_key(dst)
@@ -190,7 +194,7 @@ def _sc_sub(
     return dst
 
 
-def _sc_mul(dst: bytearray | None, a: bytes, b: bytes | Scalar) -> bytearray:
+def _sc_mul(dst: bytearray | None, a: AnyBytes, b: AnyBytes | Scalar) -> bytearray:
 
     dst = _ensure_dst_key(dst)
     decodeint_into_noreduce(_tmp_sc_1, a)
@@ -204,9 +208,9 @@ def _sc_mul(dst: bytearray | None, a: bytes, b: bytes | Scalar) -> bytearray:
 
 def _sc_muladd(
     dst: ScalarDst | None,
-    a: bytes | Scalar,
-    b: bytes | Scalar,
-    c: bytes | Scalar,
+    a: AnyBytes | Scalar,
+    b: AnyBytes | Scalar,
+    c: AnyBytes | Scalar,
 ) -> ScalarDst:
     if isinstance(dst, Scalar):
         dst_sc = dst
@@ -228,7 +232,7 @@ def _sc_muladd(
     return dst
 
 
-def _add_keys(dst: bytearray | None, A: bytes, B: bytes) -> bytearray:
+def _add_keys(dst: bytearray | None, A: AnyBytes, B: AnyBytes) -> bytearray:
     dst = _ensure_dst_key(dst)
     decodepoint_into(_tmp_pt_1, A)
     decodepoint_into(_tmp_pt_2, B)
@@ -237,7 +241,9 @@ def _add_keys(dst: bytearray | None, A: bytes, B: bytes) -> bytearray:
     return dst
 
 
-def _add_keys2(dst: bytearray | None, a: bytes, b: bytes, B: bytes) -> bytearray:
+def _add_keys2(
+    dst: bytearray | None, a: AnyBytes, b: AnyBytes, B: AnyBytes
+) -> bytearray:
     dst = _ensure_dst_key(dst)
     decodeint_into_noreduce(_tmp_sc_1, a)
     decodeint_into_noreduce(_tmp_sc_2, b)
@@ -429,11 +435,13 @@ class KeyVBase(Generic[T]):
     def __len__(self) -> int:
         return self.size
 
-    def to(self, idx: int, buff: bytearray | None = None, offset: int = 0) -> bytearray:
+    def to(
+        self, idx: int, buff: bytearray | None = None, offset: int = 0
+    ) -> bytearray | None:
         buff = _ensure_dst_key(buff)
         return memcpy(buff, offset, self.__getitem__(self.idxize(idx)), 0, 32)
 
-    def read(self, idx: int, buff: bytes, offset: int = 0) -> bytes:
+    def read(self, idx: int, buff: AnyBytes, offset: int = 0) -> None:
         raise NotImplementedError
 
     def slice_view(self, start: int, stop: int) -> "KeyVSliced":
@@ -506,7 +514,7 @@ class KeyV(KeyVBaseType[T]):
             assert isinstance(self.d, TBYTES)
             self.mv = memoryview(self.d)
 
-    def __getitem__(self, item):
+    def __getitem__(self, item: int) -> AnyBuffer:
         """
         Returns corresponding 32 byte array.
         Creates new memoryview on access.
@@ -517,7 +525,7 @@ class KeyV(KeyVBaseType[T]):
         assert self.mv is not None
         return self.mv[item * 32 : (item + 1) * 32]
 
-    def __setitem__(self, key, value):
+    def __setitem__(self, key: int, value: AnyBytes) -> None:
         if self.chunked:
             self.read(key, value)
         if self.const:
@@ -544,7 +552,7 @@ class KeyV(KeyVBaseType[T]):
             memcpy(buff if buff else self.cur, offset, d, idx << 5, 32)
         return buff if buff else self.cur
 
-    def read(self, idx: int, buff: bytes, offset: int = 0) -> bytes:
+    def read(self, idx: int, buff: AnyBytes, offset: int = 0) -> None:
         d = self.d  # local_cache_attribute
 
         idx = self.idxize(idx)
@@ -629,7 +637,7 @@ class KeyVEval(KeyVBase):
         self.scalar = scalar
         self.buff = _ensure_dst_key() if not raw else (Scalar() if scalar else Point())
 
-    def __getitem__(self, item):
+    def __getitem__(self, item: int):
         return self.fnc(self.idxize(item), self.buff)
 
     def to(self, idx, buff: bytearray | None = None, offset: int = 0):
@@ -645,7 +653,7 @@ class KeyVEval(KeyVBase):
                 return self_buff
             else:
                 raise ValueError("Not supported")
-        else:
+        elif buff is not None:
             memcpy(buff, offset, self_buff, 0, 32)
         return buff if buff else self_buff
 
@@ -678,8 +686,11 @@ class KeyVPrecomp(KeyVBase):
         if item < len(self.precomp_prefix):
             return self.precomp_prefix.to(item, buff if buff else self_buff, offset)
         self.aux_comp_fnc(item, self_buff)
-        memcpy(buff, offset, self_buff, 0, 32)
-        return buff if buff else self_buff
+        if buff:
+            memcpy(buff, offset, self_buff, 0, 32)
+            return buff
+        else:
+            return self_buff
 
 
 class KeyVSliced(KeyVBase):
@@ -1054,11 +1065,10 @@ class KeyChallengeCacheVct(KeyVBase):
         return cur
 
 
-def _ensure_dst_keyvect(dst=None, size: int | None = None):
+def _ensure_dst_keyvect(dst: KeyV | None, size: int):
     if dst is None:
-        dst = KeyV(elems=size)
-        return dst
-    if size is not None and size != len(dst):
+        return KeyV(elems=size)
+    elif size != len(dst):
         dst.resize(size)
     return dst
 
diff --git a/core/src/apps/monero/xmr/chacha_poly.py b/core/src/apps/monero/xmr/chacha_poly.py
index eb93e333..9d8d65c7 100644
--- a/core/src/apps/monero/xmr/chacha_poly.py
+++ b/core/src/apps/monero/xmr/chacha_poly.py
@@ -1,11 +1,18 @@
+from typing import TYPE_CHECKING
+
 from trezor.crypto import (
     AuthenticationError,
     chacha20poly1305_decrypt,
     chacha20poly1305_encrypt,
 )
 
+if TYPE_CHECKING:
+    from buffer_types import AnyBytes
+
 
-def encrypt(key: bytes, plaintext: bytes, associated_data: bytes | None = None):
+def encrypt(
+    key: AnyBytes, plaintext: AnyBytes, associated_data: AnyBytes | None = None
+) -> tuple[bytes, bytes]:
     """
     Uses ChaCha20Poly1305 for encryption
     """
@@ -17,15 +24,15 @@ def encrypt(key: bytes, plaintext: bytes, associated_data: bytes | None = None):
         cipher.auth(associated_data)
     ciphertext = cipher.encrypt(plaintext)
     tag = cipher.finish()
-    return nonce, ciphertext + tag, b""
+    return nonce, ciphertext + tag
 
 
 def _decrypt(
-    key: bytes,
-    iv: bytes,
-    ciphertext: bytes,
-    associated_data: bytes | None = None,
-):
+    key: AnyBytes,
+    iv: AnyBytes,
+    ciphertext: AnyBytes,
+    associated_data: AnyBytes | None = None,
+) -> bytes:
     """
     ChaCha20Poly1305 decryption
     """
@@ -43,12 +50,14 @@ def _decrypt(
     return plaintext
 
 
-def encrypt_pack(key: bytes, plaintext: bytes, associated_data: bytes | None = None):
+def encrypt_pack(
+    key: AnyBytes, plaintext: AnyBytes, associated_data: AnyBytes | None = None
+) -> bytes:
     b = encrypt(key, plaintext, associated_data)
     return b[0] + b[1]
 
 
-def decrypt_pack(key: bytes, ciphertext: bytes):
+def decrypt_pack(key: AnyBytes, ciphertext: AnyBytes) -> bytes:
     cp = memoryview(ciphertext)
     return _decrypt(
         key=key,
diff --git a/core/src/apps/monero/xmr/crypto_helpers.py b/core/src/apps/monero/xmr/crypto_helpers.py
index fe2fd0b2..9a350b65 100644
--- a/core/src/apps/monero/xmr/crypto_helpers.py
+++ b/core/src/apps/monero/xmr/crypto_helpers.py
@@ -12,26 +12,28 @@ from typing import TYPE_CHECKING
 from trezor.crypto import monero as tcry
 
 if TYPE_CHECKING:
+    from buffer_types import AnyBuffer, AnyBytes
+
     from trezor.crypto.hashlib import sha3_256
 
 
 NULL_KEY_ENC = b"\x00" * 32
 
 
-def get_keccak(data: bytes | None = None) -> sha3_256:
+def get_keccak(data: AnyBytes | None = None) -> sha3_256:
     from trezor.crypto.hashlib import sha3_256
 
     return sha3_256(data=data, keccak=True)
 
 
-def keccak_2hash(inp: bytes, buff: bytes | None = None) -> bytes:
+def keccak_2hash(inp: AnyBytes, buff: AnyBuffer | None = None) -> AnyBuffer:
     buff = buff if buff else bytearray(32)
     tcry.fast_hash_into(buff, inp)
     tcry.fast_hash_into(buff, buff)
     return buff
 
 
-def compute_hmac(key: bytes, msg: bytes) -> bytes:
+def compute_hmac(key: AnyBytes, msg: AnyBytes) -> bytes:
     digestmod = get_keccak
     inner = digestmod()
     block_size = inner.block_size
@@ -59,7 +61,7 @@ def compute_hmac(key: bytes, msg: bytes) -> bytes:
 #
 
 
-def decodepoint(x: bytes) -> tcry.Point:
+def decodepoint(x: AnyBytes) -> tcry.Point:
     return tcry.decodepoint_into(None, x)
 
 
@@ -71,7 +73,7 @@ def encodeint(x: tcry.Scalar, offset: int = 0) -> bytes:
     return tcry.encodeint_into(None, x, offset)
 
 
-def decodeint(x: bytes) -> tcry.Scalar:
+def decodeint(x: AnyBytes) -> tcry.Scalar:
     return tcry.decodeint_into(None, x)
 
 
@@ -126,7 +128,7 @@ def get_subaddress_secret_key(
     return tcry.xmr_get_subaddress_secret_key(None, major, minor, secret_key)
 
 
-def xor8(buff: bytearray, key: bytes) -> bytes:
+def xor8(buff: AnyBuffer, key: AnyBytes) -> AnyBytes:
     for i in range(8):
         buff[i] ^= key[i]
     return buff
diff --git a/core/src/apps/monero/xmr/keccak_hasher.py b/core/src/apps/monero/xmr/keccak_hasher.py
index 93b156f7..6c2d078d 100644
--- a/core/src/apps/monero/xmr/keccak_hasher.py
+++ b/core/src/apps/monero/xmr/keccak_hasher.py
@@ -3,6 +3,8 @@ from typing import TYPE_CHECKING
 from apps.monero.xmr.serialize import int_serialize
 
 if TYPE_CHECKING:
+    from buffer_types import AnyBytes
+
     from trezor.utils import HashContext, HashWriter
 
 
@@ -13,7 +15,7 @@ class KeccakXmrArchive:
     def get_digest(self) -> bytes:
         return self.kwriter.get_digest()
 
-    def buffer(self, buf: bytes) -> None:
+    def buffer(self, buf: AnyBytes) -> None:
         return self.kwriter.write(buf)
 
     def uvarint(self, i: int) -> None:
diff --git a/core/src/apps/monero/xmr/key_image.py b/core/src/apps/monero/xmr/key_image.py
index 1bbddbd3..527f4b7f 100644
--- a/core/src/apps/monero/xmr/key_image.py
+++ b/core/src/apps/monero/xmr/key_image.py
@@ -3,12 +3,14 @@ from typing import TYPE_CHECKING
 from apps.monero.xmr import crypto_helpers, monero
 
 if TYPE_CHECKING:
+    from buffer_types import AnyBytes
+
     from trezor.messages import MoneroTransferDetails
 
     from apps.monero.xmr import crypto
     from apps.monero.xmr.credentials import AccountCreds
 
-    Subaddresses = dict[bytes, tuple[int, int]]
+    Subaddresses = dict[AnyBytes, tuple[int, int]]
     Sig = list[list[crypto.Scalar]]
 
 
@@ -67,7 +69,7 @@ def export_key_image(
 
 
 def generate_ring_signature(
-    prefix_hash: bytes,
+    prefix_hash: AnyBytes,
     image: crypto.Point,
     pubs: list[crypto.Point],
     sec: crypto.Scalar,
diff --git a/core/src/apps/monero/xmr/mlsag_hasher.py b/core/src/apps/monero/xmr/mlsag_hasher.py
index 1229d7c5..37a40a2c 100644
--- a/core/src/apps/monero/xmr/mlsag_hasher.py
+++ b/core/src/apps/monero/xmr/mlsag_hasher.py
@@ -1,9 +1,11 @@
 from typing import TYPE_CHECKING
 
+from .serialize_messages.tx_rsig_bulletproof import BulletproofPlus
+
 if TYPE_CHECKING:
-    from trezor.utils import HashContext
+    from buffer_types import AnyBytes
 
-    from .serialize_messages.tx_rsig_bulletproof import BulletproofPlus
+    from trezor.utils import HashContext
 
 
 class PreMlsagHasher:
@@ -58,7 +60,7 @@ class PreMlsagHasher:
         self.rtcsig_hasher = None  # type: ignore
 
     def rsig_val(
-        self, p: bytes | list[bytes] | BulletproofPlus, raw: bool = False
+        self, p: AnyBytes | list[AnyBytes] | BulletproofPlus, raw: bool = False
     ) -> None:
         if self.state == 8:
             raise ValueError("State error")
@@ -73,11 +75,12 @@ class PreMlsagHasher:
                 for x in p:
                     update(x)
             else:
-                assert isinstance(p, bytes)
+                assert isinstance(p, (bytes, bytearray, memoryview))
                 update(p)
             return
 
         # Hash Bulletproof
+        assert isinstance(p, BulletproofPlus)
         fields = (p.A, p.A1, p.B, p.r1, p.s1, p.d1)
         for fld in fields:
             update(fld)
diff --git a/core/src/apps/monero/xmr/monero.py b/core/src/apps/monero/xmr/monero.py
index 764bfe54..bcc01fc2 100644
--- a/core/src/apps/monero/xmr/monero.py
+++ b/core/src/apps/monero/xmr/monero.py
@@ -3,9 +3,11 @@ from typing import TYPE_CHECKING
 from apps.monero.xmr import crypto, crypto_helpers
 
 if TYPE_CHECKING:
+    from buffer_types import AnyBytes
+
     from apps.monero.xmr.credentials import AccountCreds
 
-    Subaddresses = dict[bytes, tuple[int, int]]
+    Subaddresses = dict[AnyBytes, tuple[int, int]]
 
 
 class XmrException(Exception):
@@ -192,7 +194,7 @@ def generate_tx_spend_and_key_image_and_derivation(
     out_key: crypto.Point,
     tx_public_key: crypto.Point,
     additional_tx_public_key: crypto.Point | None,
-    real_output_index: int | None,
+    real_output_index: int,
     sub_addr_major: int | None,
     sub_addr_minor: int | None,
 ) -> tuple[crypto.Scalar, crypto.Point, crypto.Point]:
diff --git a/core/src/apps/monero/xmr/networks.py b/core/src/apps/monero/xmr/networks.py
index ea3d9181..d3a2940d 100644
--- a/core/src/apps/monero/xmr/networks.py
+++ b/core/src/apps/monero/xmr/networks.py
@@ -23,7 +23,7 @@ class StageNet:
 
 
 def net_version(
-    network_type: MoneroNetworkType = None,
+    network_type: MoneroNetworkType | None = None,
     is_subaddr: bool = False,
     is_integrated: bool = False,
 ) -> bytes: