Very few people even know what password managers are. If you have to onboard them into a password manager before you can onboard them into Nostr, you already lost them.
Discussion
Apple has the native keychain so that’s the default option and it’s well integrated.
But to answer your question: 1)
My bank uses QR code on browser that seems to be dynamic (moving pattern) and you point your mobile’s authentication app with camera to it and it let’s you in.