Biometric data is not a username. Biometric data is also not a password.
Biometrics is biometrics. I like to think of it sitting between a continuum between "username" and "password".
I might like a setting to require both a Touch ID (or Face ID) and a passphrase to unlock my iPhone. However, Touch ID has flaked out enough times for me (not accepting my fingerprints) that I probably wouldn't like to risk it in practice.
Biometrics is biometrics. I like to think of it sitting between a continuum between "username" and "password".
I might like a setting to require both a Touch ID (or Face ID) and a passphrase to unlock my iPhone. However, Touch ID has flaked out enough times for me (not accepting my fingerprints) that I probably wouldn't like to risk it in practice.