The problem is that people will just delete the onboarding app after they are onboarded and there is nothing to do.
It should at the very least be a note signing app (like Nostore) or something. Give people a reason to keep the app
Discussion
It would not be a problem if it did his work in the first stage.
Pairing it with a signer is a nice option, in fact I thought that Amber by nostr:npub1w4uswmv6lu9yel005l3qgheysmr7tk9uvwluddznju3nuxalevvs2d0jr5 can be a nice fit, it would only need a proper UI/UX redesign.
Or embedding nesecbunker (idea by nostr:npub1jlrs53pkdfjnts29kveljul2sm0actt6n8dxrrzqcersttvcuv3qdjynqn) using a reverse proxy like ngrok.