Huh. So they have the firmware up, and a forked project that gets FIDO2 working on an Audrino .. I don't see and CAD files or any repos that seem to contain circuit diagrams. Is the hardware something standard they load firmware on, or is only he firmware open and the hardware designs closed?

Looks it. Seems like it might be open firmware and user-space interfacing software. Didn't see any CAD/EDA repos.