They are, except they have a vendor ID that allows you to tell which vendor made the device you're talking to. You can get Passkeys by any number of vendors, but any authenticating website can decide to only allow a few vendors to log in with it.
Synchronized passkeys by both Apple and Google don't use that mechanism (attestation).
There's also the AAGUID, but without attestation, every implementation is free to provide Apple's or Google's, should websites ever start requiring that.
