If you read the parent post, the support is implemented on top of WebAuthn standard, so as far as developers are concerned, they don’t have to do anything Safari-specific to support it - their code will work fine with YubiKey or other Authenticators as well. Which is the point of web standards after all.
"Meet Face ID and Touch ID for the Web" https://webkit.org/blog/11312/meet-face-id-and-touch-id-for-...