They've had this in Sweden for like 10 years. It's all pretty clunky, even though you can now use an app instead. You generally have to have your card, then some plug-in, then the host have to implement the whole thing. Usually signing things isn't the whole story either, so you still have to deal with e.g. payments.

The Estonian system is probably better, since it's newer, but the challenge isn't really in handing out cards. It's standardizing authentication on the Internet and connecting that to whatever else matters.