Spaetzle is more southern, but a good dish all the same. Knoedel (a dumpling) would be more universal. I like Spaetzle better.
Soups are quite thin.
Cabbage is common and there's plenty besides sauerkraut. Rotkohl for example.
Potatoes are also common, salad or boiled new, but not baked.
Steering clear of sausage, then pork cutlets, roast chicken, especially with a Jaeger sosse. Leberkase, while a sort of sausage is very different from what he would expect of a sausage and doesn't look like a sausage, but loaf shaped. Ham is certainly common too.
I remember a home meal of greasy meatloaf with the grease served at the table to mash into the boiled potatoes. Not bad, but certainly not what I was expecting.
Onion tarts are quite german.
Bread is important. You'll need a whole grain rustic loaf imho, perhaps a multigrain. You can certainly get into rye and pumpernickel too.
Peas, asparagus, carrots are the vegetables I saw the most if you want a vegie side.
Green salads were rare as were melons. Lots of apples and apple juice. And apricots but not peaches.
Beer of course, and quite often some cheese.