Hi @TECHSTATIC, welcome to the community.
The first implementation will be TOTP (applications like Google Authenticator, Authy etc.). We may look at U2F/WebAuthn further down the line, but I think TOTP is worth doing first as most people already have TOTP-capable devices.
As for SSO against external providers, we have had some early discussions about this, but we don’t have any concrete plans right now.