The Flemish MAGDA platform has been built without first spending years on a grand design, but has step by step adressed concrete needs of different administrations, citizens and businesses. The EU should take a similar approach by solving concrete issues between citizens, regions or countries. We're exchanging student data between the Netherlands and Flanders to simplify their registration in another country. Why not provide this service to all memberstates, but this demands crossborder standardisation of diploma's, degrees, Personal Information ( and why not income for student grants). All within the limits of the EDPR.
(Citizens should be able to check where in any country there are data about him are used, and reuse those data themselves anywhere anytime )
Cases like this could enlarge the Single Digital Gateway step by step, Member State by Member State, slowly but surely creating a whole of Government approach.