Frozen veggies are kinda underrated for convenience and you can never go wrong with any of the many variations of beans and rice. Dry beans are cheaper, but you do need to remember to soak them the night before which I frequently don't. Canned beans are also solid.

If you consume meat its always best to buy it as whole as possible and process the cuts yourself. It's not as difficult as you would think, but it does need to be learned.

I always keep some tofu in the fridge (buy it at Asian markets for the price) because its always hella easy to chop some up, toss some spices and oil on it, and toss it in the air fryer for about 20 minutes for a easy versatile protein addition to whatever I'm making.