I have Celiac disease so for me a gluten free diet is a must
I found Germany very difficult. Many of the restaurants have an English (or some other language) menu but when you need to ask the server their English may be very limited.
Usually a salad has no gluten if I choose oil and lemon as dressing but explaining to please make sure it does not touch any bread crumbs was tricky. I ended up eating in a Spanish tapas place a few times just because it was a lot more predictable
I would bring lots of snacks - unless you speak german;
limit food to simple salads and simple meat/fish dishes with no sauce and just sautee
some of the "bio stores" were helpful for me.
I know there are pre printed cards for gluten free requests in several languages and there must be something for requesting egg free meals.
On the other hand in France I was literally asked to leave when I asked "too many questions" about gluten cross contamination. They said I will not be able to eat there anything. (and it was not a croissant shop.....)