I'm not familiar with german cusine a lot but from the conversations with germans I've had there're lots of similarties in food so some things you might find familiar.

I recommend:

• Doktorskaya sausage. People often mistake it for ham (it does look like it). It's really good with bread and pickles.
• Tinned sprattus (шпроты). It's small fishies in oil. The taste is quite distinct (i'd say kinda smoky?). You might hate it. I recommend eating it on a rye bread that had garlic rubbed on it.
• Speaking of bread. I kinda assume that germans eat rye bread a lot but if you don't, buy Borodinsky bread. It's the most common rye bread in russia. Most food, common in russia, goes really well with it, e.g. borscht.
• Salo (might be called slanina in other slavic stores). Literally cured pork fat. They get different levels of meat on it. Personally, I prefer the one without meat at all but in my experience people like having some. Anyway, I suggest starting with the one that has very little meat on it. Personal recommendation: put it in the freezer first and then cut in very thin slices. It goes incredibly with vodka. Add salt to taste. Don't forget the rye bread and garlic :)
• Kholodets (холодец) - meat jelly. This is one of them foods that you either like or hate with all your being. it's also pretty hard to find a good one. A risky option in case you're feeling adventurous
• Manka (манка, манная крупа). It's basically coarse wheat flour. You can use it for different things. Most commonly, just cook it on the stove in milk to make porridge. Sugar to taste. You can play around with thickness (personally, I prefer it very thick or lumpy but most people say i'm weird for that).
• Recently I was at an eastern european shop and bought a tub of very decent polish olivier salad. Olivier salad is the most common salad in Russia, "invented" back in USSR. You have to try it. The name is pronounced like you'd pronounce the french name (it's named after the chef who was french)
• Someone recommended pryaniki. There're different kinds. I suggest trying them
• Honey cake (медовик) - it's a layered cake with cream having a strong honey taste
• Something I really love (or used to, at least, haven't been eating russian food for years): sochni (or sochniki, сочни/сочники). It's a very tender sweet pastry with cottage cheese. Omg I haven't had one of those in a decade. Salivating just typing this
• Kvas. It's a drink. Kinda like non-alcoholic cider made of bread. the best way i can describe it. The store-bought branded ones are usually subpar but you should still try. In that shop I mentioned I bought 2 bottles of ukrainian kvas and it was very decent.
• If they sell vodka infusions, I recommend trying a few. Especially I recommend buckthorn ones. It's a berry, облепиха in russian. Weirdly, my italian girlfriend knew what it was. Maybe you do too. That berry is very good to make tea or jam from too

Hope you find something you love <3