PassKeys are definitely the future, they aren't just device-specific, they can be synced also. https://www.corbado.com/blog/nist-passkeys talks about this, though I'll admit I haven't read anything on the subject yet. But I can say that most implementations of PassKeys seem to cloud sync, including 1Password, Apple, Google, Edge, etc.

I should also add that PassKeys that are tied to devices are like FIDO2 security keys, you should be able to add more than one to your account so that you can login with a backup if your primary FIDO2 token is unavailable.

Likewise, SSO should ideally be implemented such that you can link more than one social network - and a standard email address or backup method - in addition to the primary method you might use to login with. It has always bugged me that Auth0 makes it much harder than it should be to link multiple methods of login to an account, by default.