I live in Germany, and I don't ever eat out anymore, with the sole exception of celebratory vegan sushi once or twice a year.
My experience with ordering compliant food hasn't been good. It's easy to get vegan food, but nearly impossible to get oil-free food. They'll all assure you that they don't use much oil, but of course they do—they simply don't know any better.
You will have to compromise if you go to a restaurant. In that case you'll find a great variety of traditional, modern, and international cuisine to try.
Germans are getting used to people having different diets so don't be too afraid to ask questions and to discuss your needs.
Some German words:
vegetarian = vegetarisch [vay-gay-TORE-ish]
vegan = vegan [vay-GONE]
low-fat = fettarm [FET-arm]
not much oil = wenig Öl [way-nish ALE]
low sodium = salzarm [SALTS-arm]
whole grain = Vollkorn [FOLL-corn]
small portion = kleine Portion [klah-een-ah ports-ee-OWN]
vegetables = Gemüse [gay-MEE-sah]
When I travel in Germany I live off bread, fruit, dried fruit, oatmeal, dry cereal with plant milk, pre-cooked potatoes, canned beans, canned vegetables, and the like.
Every grocery store will have some variety of compliant bread and cereal, and lots of pre-cooked vegetables in cans and glasses (albeit inevitably with some salt), and frozen vegetables.
German drug-stores which can be found in every city center (such as DM, Rossmann, Budnikowsky, or Müller) will have a great selection of "health food", especially whole grain pasta, whole grains like quinoa or millet, plant milks, dried fruit, and compliant sauces.
Other great places to shop are the so-called reform houses, "Reformhaus". They can be found in shopping centers and busy places of town. They are somewhat similar to US health food stores, so they have lots of junk such as supplements and "healthy" snacks, but also lots of whole grains, dried fruit, dried legumes, spices, teas, nutritional yeast, sauces and condiments, and lots of gluten-free and other specialty foods.
Reform houses are very typical for German-speaking regions, and are somewhat historically connected to our WFPB way of life as they are part of the larger health movement, in this case the influential so-called life reform/"Lebensreform".
https://en.wikipedia.org/wiki/LebensreformIt will be tricky choosing compliant products if you can't read the ingredients.
* avoid any ingredients ending in "-öl" which is oil, such as Sonnenblumenöl, Rapsöl, Olivenöl, Palmöl
* avoid "Schmalz" = lard
* common dairy products: Milch, Käse (and anything ending in or containing -käse-), Molke, Molkereierzeugnis, Butter, Butterreinfett, Vollmilchpulver, Magermilchpulver, Quark, Rahm, Laktose, Milchzucker
I'm probably forgetting some important ingredients. Maybe somebody already compiled some sort of phrase book/ingredient list for travelling McDougallers with translations into different languages?
If you drink alcohol do enjoy German beer, but every grocery store, bar, and restaurant will have alcohol-free beer, and most of it is pretty good and a nice treat, especially on a hot day or after lots of activity.
In Frankfurt I especially enjoyed the guided tour of the remade old city center. It opened last year. It's a breathtaking mixture of old and new architecture completely rebuilt from scratch after being destroyed in the war.
https://en.wikipedia.org/wiki/Dom-R%C3%B6mer_ProjectGermany is a great place to walk and hike. Most towns and regions will have some sort of marked hiking trails called Wanderwege. You can look them up online, or get free brochures in the local tourist information center.
June is a perfect time for riding (rental) bicycles. There are marked biking routes/"Radwanderwege" everywhere.
Most Germans are nice and helpful most of the time, and most of them speak some sort of English, but if you need some help from a fellow McDougaller send me a message.
So mostly we cook our own food. We were there during strawberry season and spargel (asparagus) season, as well as getting new crop potatoes. See, no translations necessary. I even did it at farm stands, just point and pay, and say thank you. 
