I feel like Indian food ought to be easy? Slap some non-soy legumes in there in place of the paneer and go to town. Palak chickpeas, chickpea tikka masala, etc. People on the Indian food sub love sniping at each other about whether coconut milk is authentic or not but it has a thicker, creamier consistency than most other plant milks and is gluten free. I feel like curries or stir fries in general would be fairly easy, especially if you can get a couple big bags of frozen, pre-chopped cauliflower or green beans.

It also seems like a lot of soups would work and be easy to bulk. Make mirepoix but sub cabbage for the celery and go from there. If you can find some sort of gluten-free bread that doesn’t have any of the other stuff in it, you can try making matzoh ball soup. (I tend to use chickpea water for the eggs when cooking for vegans which works for most things.)

Also, oats do not contain gluten themselves, they are just generally processed on equipment that also processes other grains that do have gluten. (I used to buy gluten-free oats when I was baking for my ex who had celiac and was sensitive enough she had to switch toothpastes, which is not a substance that I ever thought about containing wheat products but there you go.) So you might want to double check with the person with the oats restriction. They’re filling and cheap and versatile and healthy. Pulled oats are a big thing here if people are sick of tofu and beans.

I googled sulfite allergy and found this list which might be helpful to you. Apparently both bottled lemon and lime juice have them so be on the lookout for that with whatever recipe you pick and maybe use a low sulfite vinegar instead

Overall, with that sort of a list of allergens, I would go for very minimally processed stuff wherever you can. Some sauces have yeast/wheat products. Lots of hidden things.