Oddbean new post about login | logout You don't have to rely on an extension any more - there is remote key access protocol nip46, try nsec.app as one implementation. There is Amber offline signer for Android, not sure if it plans/supports QR codes though.
Yeah seems like amber is what I'm thinking. Nip-46 seems needlessly complicated though. You can do so much with it, but the up front setup cost of something like an nsec bunker for the average person is a lot.