First of all excellent maps everyone is doing. I’ve been lurking for a long time but a little nitpicky detail I’ve noticed made me want to post again to help out.
The Swedish-Norwegian border was largely undefined until the Strömstad treaty 1751 so for example the area in the north on this map...
I think the Reichsgaue is a bit of a tricky situation. Given that the länder were left in place but the real power laid with the gauleiters and not the minister presidents of the states.
https://en.wikipedia.org/wiki/Administrative_divisions_of_Nazi_Germany#Gaue.2C_Reichsgaue_and_L.C3.A4nder