Thank you for your writeup. This sounds like a combination of unchained (collab custody) and bitkey which is a new offering from Block.

It sounds interesting. If I may... from my own research and experience it is far, far better that users generate keys offline through either hardware wallets using signed firmware... or through secure computing environments (TAILS OS).

And for most normies, whether it's single or multisig, hardware wallets are a significant upgrade in key generation and management from any kind of operating-system generation... that is generating and managing keys while offline.

If you haven't tried it, Nunchuck does this really well. Different keys can be put into a multisig via different methods - USB, QR code, NFC, and through hot wallets. Then they can be signed 'offline' and conglomerated on the phone app nunchuck.

It's not perfect... but it is pretty user friendly and they offer a paid service where one or more keys are kept encrypted by the company running the service.