You can search for vegan trekking food. There's plenty of brands selling convenient products (e.g. trek n eat) where you just have to add hot water. But you'll also find many recipes to prepare such meals youself.

Some inspiration: cous cous, instant pasta, powdered hummus (must be made from roasted chick peas as raw ones are toxic), tomato soup. For protein you can add nuts, seeds etc. If you don't care for the weight, you can also buy pre-cooked rice etc. and just add an instant soup to heat it up.

I always have a pack of nuts in the bag I take to work. If you get the mixtures with dried fruits/berries in them, those are probably a bit easier to digest, too.

Lots of cereals are vegan, protein bars, breakfast bars. Trail mix. Energy bars. Light weight. Easy to travel, packs nutrients and calories to carry you through the day. While you might not feel full keep in mind that you are consuming the necessary calories.

If you can spare the (relatively minimal) time you can reheat anything by putting it in a container and sitting it in hot water. Like a throw dhal in zip lock bag, partially fill container with hot water, put bag in hot water and lid it. Wait 10 minutes, enjoyed warmed food. So anything you can fit in the fridge you bring with you or get but needs heating can be heated that way.

glass, metal, or thin plastic will be best for the inner container (assuming glass is able to withstand thermal shock, e.g. borosilicate and not ice cold) as they're thermally conductive. Tight foil wrapping does the same thing too but more chance of leaks. Or you could use those hot water resetting hand warmer type packs to supply heat in an insulated lunch box type thing and reset of an evening for a warm lunch while out.

Stuff like quinoa or couscous cook in hot water so with fresh veg and a sauce make some sort of bowl? Salady but substantial at least.

Buy silken tofu, pack seaweed and miso. Quick light soup? boring but better than nothing.

That's all I've got soz. GL!

EDIT: oh actually a solid esky and occasionally restocking ice/cycling cold packs from minifridge freezer can be an impromptu freezer if you want to being some frozen meals that stay good fridged for a week.

Also the staff at the hotel might microwave something for you in the break room if you are nice to them.

Instant potatoes.

Additionally, a rice cooker is amazing in these situations. Like a mini stove/burner. If within your means, bring one!

Popcorn, fried onions, noodles, good old rice.