Hey K. -
I don't cook as much as I used to either and have resorted to prepared foods, but I'm careful of what's in them, trying to get things that are made of a short list of ingredients. What brands do you buy? Since I don't know, I'll go with the suggestion that you can still give him all of those things, but "clean" them up a bit by buying them at places like Trader Joe's, Whole Foods, or Wild Oats. They offer frozen pizzas, chicken nuggets, hot dogs, mac&cheese, but if you read the label and are careful to get those without trans fats (hydrogenated oils) and high fructose corn syrup, you're better off right there. Also look for lower fat and salt content. As far as hot dogs go, I personally stick with chicken or turkey, but if you prefer beef, look for something w/o nitrites. Not sure Hebrew National has that or not, but it's a brand I allow my daughter to eat if we're at someone else's house & that's what they have. I've relaxed a lot in the last year or so.
Does your son like soup? chili? pasta? casseroles? My daughter likes all the things your son does but fortunately likes veggies too so I can always give her something simple like a couple of slices of pizza & some steamed veggies. Happiest of all, she LOVES soup and will eat almost anything if it's in a clear, tomatoey broth. You can whip up a pot of soup very quickly and if you don't like standing & chopping for a long time you can use frozen veggies or buy them already chopped. I add cooked beans and sometimes quinoa to a pot of soup to make it more filling. You can toss it all in together in 15 or 20 minutes, let it simmer for a half hour & your done. A big enough pot of soup can last for a few meals, with addition of quesadilla or garlic bread, chicken nuggets, etc.
Oh - another idea. See if he likes eating roast chicken. I sometimes buy an already cooked whole chicken at Trader Joe's or Whole Foods and they are both delicious. After the first meal or two, you can do a lot of other things with it in other meals. We get lots of mileage out of them.
Bon Appetit & all the best,
Colleen