Chrome 70, just released, supports WebAuthn with biometrics. This includes Touch ID on macOS. I was playing with it this morning:
I can’t wait for Apple to get in the game here: if Safari supports WebAuthn and biometrics in some future release of iOS and macOS, and ties it to iCloud Keychain, we might really see passwordless authentication take off on the web. Porting private keys outside of a single ecosystem might prove to be a stumbling block at first… but it’s still a step in the right direction.