Safari is late in the game when Firefox launched support for WebAuthn earlier this year, followed by Google with Chrome. Individual sites and apps also support the standard, including Twitter, Facebook, and Office 365.
USB key authentication is another option for two-factoring systems that use SMS text messaging or apps like Duo or Google's own authenticator , However, hardware keys are particularly effective – Google has completely eliminated phishing attacks by providing its own Titan Key hardware to 85,000 of its employees (above).
That does not mean that they are flawless. If you lose the key, you might be in a world of injuries, though the same logic can apply to passwords and other systems. You also need to carry an extra device as if you did not have enough keys, dongle and cards. If you're curious to give it a try, Safari Preview 71 is now available for download – of course there is no guarantee that the feature will be widely publicized.