If you want to consider non-extradition as measure of real sovereignty, then you’ll note from your parents article that a lot of European countries are on that list. In Germany, extradition of German nationals is barred on constitutional grounds (1) with the notable exceptions of extradition to other European states on the basis of the European Arrest Warrant and to the International Court. Similar exceptions apply in France, which is also bound by the European Arrest Warrant.

(1) https://www.gesetze-im-internet.de/gg/art_16.html

Isn't this a civil case? Would extradition even apply?