If you want warm meals, one of these might be handy. You could just throw whatever you want in a pyrex, plug it in, and will hold it at a warm temp until wanted. I have the regular non-vehicle version and I’ve had good luck.
Most things will last till lunchtime if you prepare it the night before and store in tge fridge or prep it in tge morning. For example prepping a salad of things like kidney beans, peas, tomatoes, etc, maybe with chicken slices or some other lean protein and almonds for healthy fats. Can place it all together in a plastic container/tub and eat at lunch
A wrap or sandwich with a meat and a veggie. Get a cooler bag, an ice pack can help keep things cold for longer. Snack on fruits and nuts. Soup or stew are other options if you have a thermos. Get in the habit of meal prepping now and not getting fast food. It’s so much harder to stop eating fast food daily once you get used to it. It won’t be good for you in the long term.
I’ve been in a similar situation of long shifts with no fridge! My favourite healthy lunch was a falafel wrap. Wholemeal wrap, \~3 falafel crumbled up, veggies (usually spinach and tomato for me), some cheese, and some aioli, but you can add whatever you want. As mentioned before an insulated lunch bag with an ice brick helps keep things fresh, and because it’s vegetarian you don’t need to stress about food poisoning :)
Using a lunchbox with an ice pack can keep almost anything unspoiled until lunch.
Massive range of sandwiches and salads at your disposal. Check out sites like: https://www.themediterraneandish.com/category/salads/ for ideas
In cold weather, a thermos flask of soups and casseroles is an option.
Make extra for dinner. Whatever that’s supposed to be served warm, save a portion in the fridge, microwave in the morning and store in thermos for lunch. For food that’s served cold, use ice packs in your cooler bag.
I’m a college student, so I have a similar eating-lunches-on-the-go problem. I go for veggie sticks, fruit (usually grapes) and some hard boiled eggs/cheese or a wrap. Sometimes I’ll throw in a Greek yogurt for a snack. I keep it in the fridge over night and haven’t had any issues by lunch time.