@elilla Can be a bit hard to find, and I haven't actually used these for navigation (yet), but if you can get an Amtliche Stadtkarte/Stadtplan those are quite nice as they include all street names in a city and some house numbers.
The Heidelberg one I was given by some people in Rathaus who initially didn't know that they even sold them, the Mannheim one I randomly stumbled on in a bookstore. Some cities stopped printing these unfortunately:(