@mwichary How far north might you get?
At the Deutsches Museum you'll want to make sure you check out the Dehomag they have. Quite rare.
There is this museum that I've never been to: https://randoc.wordpress.com/2017/01/15/an-ibm-museum-in-germany/
There's also this, which I haven't visited: https://www.f05.uni-stuttgart.de/informatik/fachbereich/computermuseum/