[mroche]

This is obviously kicking the can down the road, but I "solve" this problem by storing passkeys in a third-party credential manager that supports them. That way I can use them on any device that I've installed the client app or browser extension on. I have this working on Fedora, macOS, Windows, and iOS.

But again, kicking the can down the road.

[deltoidmaximus]

Well, you can until they use the attestation feature to block your passkey manager implementation.