microg got FIDO support end of last year, even nfc got along since, see this user feedback. Lots of open issues on the topic tag [FIDO] so “ymmv”.
In the context of /e/, I think it’s up to bromite now to use it - https://github.com/bromite/bromite/issues/2339
Not sure where Firefox is at currently, they moved issues to their bugtracker and previously relied only on the gplay implementation.
I have a hardware key, will trial it this week and report back.