Comment by zimpenfish

> the dumb and lazy way is to SSO through a government managed portal with OAUTH2

The weird thing is that UKGOV already has this for the NHS - my GP's app uses access.login.nhs.uk to log me in. That could easily verify my age to another system.

(Admittedly it's not sufficient for the wider case because not everyone is registered on nhs.uk but it does show that UKGOV has the capability to do this.)