WebAuthn is a W3C published standard for Web Authentication. It comes from the Fido Alliance which has some pretty big names as members.
Support also looks pretty good across browsers. Global support is at 68.26% today.
All of this suggests that now is a good time to start using WebAuthn.
This is the full list of sites I know of that are using the standard.
Both of these are examples sites for the standard, so I am not sure they count.
Please help grow this list by sharing any other places you can make use of WebAuthn.