The difference with Public is the user has to trigger the sign-in process with a sign-in action manually (new pin not required). Whereas the other authentication methods have the sign-in process triggered on app load. Not great either way. If you have users (like myself) that constantly close apps they will become frustrated no doubt.
Note I’ve only tested on iOS with installed apps.
To “fix” this from “where I sit” and not break their current “auth flow” they would have to automatically trigger a sign-in action on app load.