Can’t they just eat more of the same items instead of needing extra sides?
For burgers (or pulled pork/chicken) sandwiches: salad, corn, cole slaw, pasta salad, baked beans, cucumber salad, Mac and cheese
With pasta: salad, bread or garlic bread, roasted veggies, broccoli salad, sautéed green beans,
Chili: serve over pasta, rice, or garlic bread. Increase the beans in it.
Add roasted sweet potatoes with any meat/starch/veg dish.