As it is we're seeing companies capture IDs and face scans and it's incredibly invasive relative to the need - "prove your birth year is in range". Getting hung up on unlinkable sessions is missing the forest for the trees.
At this point I think the challenge has less to do with the crypto primitives and more to do with building infrastructure that hides 100% of the complexity of identity validation from users. My state already has a gov't ID that can be added to an apple wallet. Extending that to support proofs about identity without requiring users to unmask huge amounts of personal information would be valuable in its own right.