I envision it being similar to passkeys today. I'd expect that your smartphone would hold the credential, and you use the standard QR-code flow for most users.

I envision it being similar to passkeys today. I'd expect that your smartphone would hold the credential, and you use the standard QR-code flow for most users. I store my passkeys in a password manager, so it's conceivable that they can be portable... but in ways supported by the FIDO alliance.