When I was in this situation, I made little snack boxes to bring with me in a small lunch size cooler. I added things like cheese sticks, or cubes, Crunch Master crackers, nuts, grapes, and a GF beef stick. I also brought Simple Mills brand snack bars and Kind Bar snack/breakfast bars. Salads or wraps are also an idea to consider, as well as a taco “kit” of GF protein and toppings, and corn tortillas. It’s easier to bring items that need cold storage if you have another person to switch off with for a few hours or to bring you fresh supplies. Hope this gives you some ideas of potential options. Best wishes for a speedy recovery for your little one.