Here is some options

squeeze tubes of pudding and peanut butter. I put the PB on tortillas for lunch.

I know many do this also but noodle dishes with tuna or chicken or rice-a-roni with the same.

Power bars for lunches. I like Clif bars-they are easy, quick and give lots of energy and nutrition.

sugar free crystal light or tang. Comes in very small plastic container that makes 2 quarts of drink each. Can fit inside of a cup or cook kit. Takes up no room and easy to mix.

Breakfast bars-oatmeal or milk and cereal bars. I used to bring pop tarts for quick no cook breakfasts. Now I go the oatmeal breakfast bars if I do not want to cook.

Those are a few