A new login technique is becoming available in 2023: the passkey. The passkey promises to solve phishing and prevent password reuse. But lots of smart and security-oriented folks are confused about what exactly a passkey is. There’s a good reason for that. A passkey is in some sense one of two (or three) different things, depending on how it’s stored.
Passkey plus TOTP doesn’t really make sense (they’re both client side cryptographic keys, you don’t need two protocols), at least use a PAKE algorithm with a PIN instead if you want the server to be able to check the user’s knowledge of a secret without sending it in a readable form