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...
Agreed, my main issues with hardware keys are that so few sites support them, and the OS support is kinda bad like in Windows the window pops up underneath everything and sometimes requires a pin entered.
I also hate that when I last looked nobody made a key that supports USB-C, USB-A, and NFC. So now I’ve got an awkward adapter I need to carry on my keychain.