Note that they were bought by Akamai last year. I wouldn't count on the Krypton apps staying around, at least not in their current incarnation. A fork could survive, though.
Thanks, that reminded me of upcoming iOS 14 support for WebAuth/FIDO. Perhaps that can be extended to SSH auth.
Do you mean with Face ID? Since WebAuth/FIDO already work with iOS 13. I have been using U2F with my YubiKey (whichever one has NFC).
Not quite. The point is to use just the iPhone as the authenticator, without an external token.