Correction, resident keys are used for usernameless authentication (you don't need resident keys for passwordless).

I recently (last week) wrote a Django library for WebAuthn (https://pypi.org/project/django-webauthin/) and use it on a few of my sites (https://www.pastery.net, https://www.eternum.io and https://www.deadmansswitch.net, if you want to try it out).