I don't think that a 100% anonymous attestation protocol is what most people need and want. It would be sufficient to be able to freely choose who you trust as

I don't think that a 100% anonymous attestation protocol is what most people need and want. It would be sufficient to be able to freely choose who you trust as proxy for your attestations *and* the ability to modify that choice at any point later (i.e. there should be some interoperability). That can be your Google/Apple/Samsung ecosystem, your local government, a company operating in whatever jurisdiction you are comfortable with, etc.