Tip: The iPhone Passwords App has basic TOTP functionality (manually create a password entry and click “Set Up Code”). I have a few dummy passwords which are effectively just labels for some login codes - it’s one less App to install.

Unfortunately Microsoft Authenticator does more than TOTP and usually its not up to the user to decide which two factor implementation is accepted.

Some Microsoft setups ONLY allow Authenticator - can’t use 1pass etc. I have recently fallen into this pit