WebAuthn doesn't preclude the use of biometrics locally. Whether you securely store and use a private key in a discrete hardware key like a U2F token, or in a computing device's TPM chip secured (locally!) by a biometric access check; it boils down to the same mechanism WebAuthn describes.

WebAuthn rightly does not push biometrics beyond what you can do with them on a local device. It would be a privacy nightmare!