My 2 cents is major app devs need to agree to stop allowing priv key logins (or at least hid them in a sub-menu) and only extension or bunker. But that would mean every iOS app would stop operation.
Discussion
Yea I think there are two situations:
1) Nostr client login
2) Platforms that allow you to login with Nostr
Eventually #1 will be everything, but in the meantime there will likely be a lot of #2s. For #2 the platform just has to be able to prove you have ownership of your npub, which can be accomplished through DM