WebAuthn does not mandate any kind of form factor[1], external tokens use CTAP for USB/Bluetooth/NFC, Apple FaceID/TouchID and Windows Hello using proprietary interfaces with the built-in hardware. Blink-based browsers ships with a virtual authenticator for debugging[2] and there are a few more[3].

Apple and Google already announced cloud syncing earlier this year, using "passkey" as a friendlier term for end-users. QR codes already allow for cross-ecosystem non-synced use cases, like using my personal Android phone to log in an account with my work Macbook. https://securitycryptographywhatever.buzzsprout.com/1822302/... is a good listen to catch up on the latest developments.

[1]: https://www.w3.org/TR/webauthn-2/#authenticator-model [2]: https://developer.chrome.com/docs/devtools/webauthn/ [3]: https://github.com/herrjemand/awesome-webauthn#software-auth...