Thinking about more post-war content, I have always been thinking about post-war Belgium. It is obvious that Wallonian collaboration with the French nazi's would be rather large, seeing as they get cores on the land. The ethnic tension in Belgium is already referred to in the events regarding the Treaty of Strassburg. Also, knowing that France seeks her natural borders, a Francization project would be set up in the Rhineland, Flanders and Southern Netherlands to "bring the population back to their proper French ways".
First maybe a bit on the Treaty of Strassburg since it mentiones the "Flemish dominance of the Belgian state", which I think would not be the case. OTL, the Flemish movement was one of the main actors on the Belgian right. The Flemish movement had received a certain "boost" from the occupation and collaboration with the Germans, but also legitimization by fighting in the trenches (Hier ons bloed, wanneer ons recht). Now, what would change if it was the French Empire that invades? Well, I do not think that collaboration would happen on the same scale it did OTL. France would be more interested in, already, the potential annexation of Wallonia and even Brussels. Not to forget that the Flemish lads would be dying together with Germans and Dutch in the trenches at the Meuse and Moeselle. Interbellum Belgium would likely see a degree of federalization that only happened post WW2 OTL.
What would happen after the war? Albert's government would return to Brussels (assuming the British take the land, what the Soviets would do with it is a much more open question). Albert, now twice triumphant would get assassinated by Wallonian radicals. At that point you can get the option to let the elections go ahead or postpone them. If you postpone, you'll get one after the country is stable again. If you let them go ahead, the Flemish radicals (probably lead by Van Severen) can get the chance to become the dominant Flemish force. Wallonia will react with increasing anger, until a revolt of Wallonian nazi's breaks out, probably lead by Degrelle. It would be crushed, but it would seal the fate of Belgium. Flanders and Wallonia would break up, Calais could be returned to France and perhaps Flanders and the Netherlands would unite
