I'm thinking of writing a Django-webauthn library (although I'm not sure if it would just be simpler to fork django-u2f). Would the Python library help at all? It looks like it's for USB communication and not for general helpers around signing/authentication/etc.
It's mostly for host-authenticator communications, yes, but it it includes a couple of helpers for verifying signatures. But you're right it's not a full-featured server library at this point.
