Nazis weren’t nationalists. A nationalist believes in nations with borders, language and culture.
The Nazis SURE didn’t respect the borders, language and culture of other nations.
The Nazis were certainly German nationalists.
The Nazis wanted to impose themselves on the entire continent. Once the war started, Hitler talked in terms of being the leader of the entire continent, and not just Germany.
Hitler wanted a bunch of puppet states subservient to Berlin. Substitute Brussels for Berlin, and you have the EU.