EU digital identity law to make inter-EU signatures (And authentication) work.
As an example, an EU citizen working in Sweden should be able to submit Swedish tax forms whilst living here by using a digital identity from the originating nation.
There are also some standards in place like ETSI standardized extensions to PDF signatures so that you can verify that a signature inside the PDF was actually signed by a specific physical person (the standard is there but it's not fully used throughout the EU yet due to some legacies).
Implementation is a bit of a mess still but things are converging.
As an example, an EU citizen working in Sweden should be able to submit Swedish tax forms whilst living here by using a digital identity from the originating nation.
There are also some standards in place like ETSI standardized extensions to PDF signatures so that you can verify that a signature inside the PDF was actually signed by a specific physical person (the standard is there but it's not fully used throughout the EU yet due to some legacies).
Implementation is a bit of a mess still but things are converging.