> I can't use a passkey on a device unless I can install my password manager on that device and I am comfortable giving that device access to my passkeys.
That's simply not true. I'm able to log onto GitHub on my corporate device using a passkey that's kept in 1Password on my iPhone.
That's fine if you've got a couple of supported devices. The hardware support is however very bad. If my hardware is unsupported (and most hardware in the world is unsupported) that's not very helpful.