This announcement from last October is a huge deal.
"Meet Face ID and Touch ID for the Web" https://webkit.org/blog/11312/meet-face-id-and-touch-id-for-...
"Meet Face ID and Touch ID for the Web" https://webkit.org/blog/11312/meet-face-id-and-touch-id-for-...
Safari may support Face ID and Touch ID, but I doubt it would be in anybody else's best interest to also support it.
Not that it matters anyway, since on iOS they all use Safari...