Potatoes have a long shelf life and even then it’s not a clear win.

A medium potato is around 110 calories. 15 * 150 calories servings = 5$ that’s 20.45 medium potatoes for 5$ or 24.4c per medium potato. https://www.walmart.com/ip/Doritos-Nacho-Cheese-Tortilla-Sna...

The potato requires prep, 10 minutes in the microwave ~= 1/4 kWh, and presumably a little salt and butter. A microwave meal is a more complete nutrition source and takes less time, making them more complex point of comparison.