[dahauns]

Apologies that I'm latching onto your post for visibility, but for the sake of discussion - the European Identity Digital Wallet project specification and standardisation process is in the open and lives on github (yeah, the irony isn't lost on me :) ):

https://github.com/eu-digital-identity-wallet

https://eudi.dev/latest/

Everything's very much WIP, but it aims to provide a detailed Archictecture and Reference Framework/Technical Specifications and a reference implementation as a guideline for national implementations:

https://github.com/eu-digital-identity-wallet/eudi-doc-archi...

https://github.com/eu-digital-identity-wallet/eudi-wallet-re...

https://github.com/eu-digital-identity-wallet/eudi-doc-stand...

You'll find several (still evolving) Technical Specifications regarding ZKPs (including a discussion area) in the latter.