If this were an interoperable standard, I imagine the pool of "approved issuers" would be relatively small, limited to e.g. governments or banks. Bloomberg uses

If this were an interoperable standard, I imagine the pool of "approved issuers" would be relatively small, limited to e.g. governments or banks. Bloomberg uses a system not entirely dissimilar to this[1], and I could see Apple and Google building an OS API that the issuers' apps would use specifically for this. 1. https://security.stackexchange.com/questions/101862/what-advantage-does-the-bloomberg-authentication-system-have-over-traditional-2 https://security.stackexchange.com/questions/101862/what-adv...