GrapheneOS No, it doesn't protect privacy in any way.
A possibly related question I have. Does hardware-based strong attestation in general, Google Play Integrity specifically, have a unique persistent ID similar to the MediaDRM ID, that can be used by apps and the associated web service to fingerprint that the app is running on the same device as another app, or that the user is the same user as before, even across different profiles? Is this persistent ID changed after a factory reset, or it necessarily needs to be the same because of relying directly on some kind of factory provisioned or factory generated key pair? If it is persistent, are there any plans to block all attestation as well, based on a per-app toggle, similar to the plans for MediaDRM?