You could have the additional key be offered by the person who onboarded you too 🤔
Like an “affiliate + key assistance” system. As long as they understand the trust model, this could be an interesting idea.
Also I think a way to hold the “backup” key with a friend or spouse using Apple keychain or Google password whatever would be critical. I think having them use an entirely different app and download it would be a bit friction for someone who didn’t have any bitcoiner friends. But if you could have a way to have a secure keychain encrypted key or something, and your wife or friend could just scan a QR and unlock something for you, that would be good UX. They wouldn’t even have to know what keys are being used or where. They just know that their Apple account has the keys to help get your coins back. 🤔🤔
Something there I think.