WebAuthn rocks, but you might feel that nobody uses it.
Fortunately, you are wrong!
Visit 2FA Directory: Global or 2Fa Directory: USA for a list of popular sites and whether or not they support two-factor authentication.
This site is pure gold: it gets you up and running with WebAuthn everywhere possible as quickly as possible. When the provider doesn’t provide it them contact them demanding it.
Here is their codebase: geniuses.