The main problem with passkeys is that perfect became the enemy of good. Passkeys 1.0 should have been nothing more than an exportable private key synced by your browser or password manager.

Instead, the push for storing them non-exportable in TPMs means that the UX is completely busted when trying to use them across Microsoft/Apple/Google/Linux.

I'm currently considering adding passkeys to my services. If I do, the plan is to attempt to detect if the user has a password manager and only offer passkeys if yes. It's the only way I've thought of to ensure decent UX.