Maybe the onboarding should be a separate application?
No NIP-07 extension? No problem! 😀
I'm working on adding a simple #Nostr onboarding experience to nostr:npub1lstr2kmdthkgfuzne8e4cn2nhr646x8jt25szdj7t4wr6xemtuuq3lczsj right now. If you try and log in with out a NIP-07 extension installed, it'll prompt you and walk you through key and profile creation.

Discussion
I’ve gone back and forth on this idea. My current thought is that it’d going to be best in app but generalized in a way that makes it fast and universal. Probably using something like NsecBunker.