I wonder if the best way to resolve this is to have a kind 1 client as a user's initial onboarding client, that gets them set up with a private key, their profile, and allows them to have a NIP-60 wallet right away or connect a wallet of their own, and then can be used as a signer app for any other Nostr app they want to log into. That way it is still just one app that has their nsec, and provides them instruction to back it up, of course, but also only one app that a new user needs to install to get onboarded.