We had originally planned to go all-in on passkeys for ONCE/Campfire, and we built the early authentication system entirely around that. It was not a simple setup! Handling passkeys properly is surprisingly complicated on the backend, but we got it done. Unfortunately, the user experience kinda sucked, so we ended up ripping it all out...
Yeah it’s truly a shame almost no site other than google and github support hardware security keys.
For your case you would probably want a yubikey 5c and then a usb c to usb a adapter yeah. I wish for a usb a and c and nfc as well.
I’ve got one each of the USB-C and USB-A versions. The USB-A is actually the one that lives on my keychain as the connector is more robust against debris and I was able to find an adapter that is on a lanyard.