For Australia (who will need something like this this year per current legislation), the only sensible location is the government my.gov.au central service portal. None of the other services have an incentive or requirement to do it (Medicare, drivers license issuers, Centrelink). And given the scope of the rollout (all major social media, as nominated by the gov), it would need almost all of the banks or super funds to implement the same API for the project to not fail.

But I don't think anyone has told my.gov.au that needs to happen, so we are either going to get some proprietary solution from social media companies (tricky, since they will need to defend it in court as they are liable, but maybe discord saying 'best we can do sorry' or 'better than our competitors' will let them off). Or just switching off the services for a few days until the politicians panic about the blow back and defer the rollout until some committee can come up with a workable solution (ideally in the next election cycle).