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...
With a password manager I’d argue its better but supports still not all there yet. I am waiting on bitwarden right now to support mull, basically its blacklisted, but it was added in the last 2 weeks so now its a waiting game.