

Hi! Sorry just saw the question now.
In the TrollThrottle paper, we used Direct Anonymous Attestation (https://en.wikipedia.org/wiki/Direct_Anonymous_Attestation#Privacy_properties); the EU ID proposal is different but there are techniques to achieve a similiar property. At a high-level, the issuer provides a value that can be turned into pseudonym by randomizing it. The verifier (essentially everybody) can see that the result is a randomized version of something provided by the issuer, but the issuer cannot tell one user’s pseudonym from another.
As lemmy is federated, nations/groups/blocs/whatever, can come up with their own system or adopt this system. What matters is who (instances or even end users) is recognizing the identity provider’s authority and willingless to ensure each person has just one identity.
If I am convinced your local ML group is making a good job ensuring everybody just registers once, I can display this along with the message.