[StavrosK]

I implemented this mode in a Django library [0] (demo on www.pastery.net) because I love the idea of not needing a password manager any more, just simply having a key with you to log in anywhere, but it doesn't seem to have widespread browser support yet.

Maybe I made a mistake, but Firefox doesn't seem to work very reliably with it, and mobile support is spotty too.

[0] https://pypi.org/project/django-webauthin/

[tialaramex]

Yes, resident credential (aka "Client discoverable") support in (at least) desktop Firefox is broken and has been for a long time. I believe it's also absent (but at least not broken) in desktop Chrome. :/