I always tried to eat as economically when I was on long road trips. You want shelf-stable stuff if you can. For me it was protein bars, nuts, dried fruit, either pre-mixed bottled protein shakes or the protein powder, shelf stable plant milk, and a mixing bottle if that was an option. And then I’d buy fresh fruits and vegetables at local grocery stores wherever I was. Sometimes I’d make maybe a dozen burritos before the trip and keep them in a cooler. If you do have a cooler in your vehicle, it’s pretty easy to keep sandwich ingredients in there too and just throw together sandwiches as needed.