Note: I now merged three other Feature Requests (FRs) requesting the same thing with this one here.
@Pieselos You wrote “login” - but currently, there is neither a way to login to the Bitwarden mobile apps with biometrics nor with a PIN alone - let alone with both -, so I think you meant “unlock”. (as locking and unlocking would be the main way to access any BW app)
If you want to be able to use biometrics for login to the BW apps, I would suggest to have a look at this FR: Sign into Bitwarden with a passkey / "Login with passkeys" (for all BW apps) (with a passkey, you would be able to use biometrics, depending on where you store the passkey)
PS: I added “(for increased security on the mobile app)” to the title of this FR.