Do all EU countries have that? I know our (German) ID works that way, using the FOSS AusweisApp, but I hadn’t heard of it being EU-wide (it should be, though).

It's been a slow rollout but yes, it's an EU wide thing. Slovenian IDs issued after around 2022 have them too.

Spanish ID cards have had an X. 509 cert inside them for more than 10 years, I use it all the time to sign documents and access government sites. There is already legislation and a push for an EU-wide digital identity wallet that should be up and running this year, look up eidas 2.0 and the EUDI wallet.

That looks like it should make things like privacy compatible age verification "trivial".

Thanks, that looks very cool, and apparently close to coming into effect.

It's nice that the platforms don't get access to data, but does the government gets information about who is trying to access what?

Yes, it has been possible for a long time to provide anonymous attestations. But somehow, they also always seem to require that you have something like Google play services running for you to ask for the attestation in the first place. And with PKI, even though they could do with just the public key, they somehow also always insist on generating the keys for you (so they have the private key as well).