What do you mean by "appetite of a 10yo” ? 10yo that are 75% vegan are not rare and the appetite comes with habits. Changing is far easier for a 10yo than a 75yo.

Why "cook”? In a hurry I grab a can of bean, a carrot, a branch of celery, some rye bred and a square of tofu. No prep or tooling except a spoon for the beans.

Something hot at the snack? Grab a veggie pad thaï, veggie pizza, veggie burger (with actual veggies), daal with veggies…

If all you eat is junk food, I think the vegan food industry has already pretty much solved that part.