Flavor does not matter, presentation does not matter but the food shouldn’t make you sick, and should ideally have enough calories per day for the average person to survive (2000 kcal min).
Edit: I am not in any danger of starving or malnutrition, nor am I insolvent. I’m mainly asking this question out of curiosity on how people would approach a solution :)
Oatmeal and rice in bulk is cheap as fuck and great foundations to build almost any style or cuisine type from. Add protein and/or fruit and/or veg that best fits your budget and nutritional needs. Meal prep the fuck out of your favorites and you’ll have a great system to tweak and fit to an adapting budget.