Passkeys are a potentially good technology, that is frequently implemented in an insecure and user-hostile way.
Good: a standard way for authentication that can be implemented in common on client and server, such that the user doesn’t need to know a secret.
Bad: Most OS and platform vendors breathlessly implemented this standard using their proprietary APIs and making it practically infeasible (read: impossible for typical end-users, therefore they won’t, therefore insecure) to attempt syncing your passkeys outside their walled garden.
It is entirely feasible to implement passkeys in a way that users are in control and can freely move between devices and operating systems. But many implementations make that impossible, while still calling their implementation “passkey”.
So, we need to reject any implementation which puts any barrier to the user freely migrating and syncing all their devices regardless of platform.
—Groucho Marx