You can’t use any random password-manager with passkey support.
I use Bitwarden for everything and have to have MS Authenticator installed just for this 1 login.
Super annoying.
I have Duo in our environment. Authenticator not required.
You can use any credential manager you choose for Microsoft Account passkey.
The use of a passkey doesn’t require Authenticator or other OTP app. Gemini said that an OTP app can be used as a vault for the passkey, but it’s not the mechanism that permits the check of the private key. Rather, that’s the PIN or biometric. Now, perhaps I don’t understand your statement and you can clarify if that’s the case.