You can open up many avenues of feeding yourself "well enough" if you reconsider your definition of a meal, and consider actual cooking/food prep to be an option.

Cheap and storage-friendly ingredients off the top of head are potatoes, rice, (dried) pasta, flour, cheese, eggs (no need for refrigeration, just don't wash off the protective layer), onions, garlic, tofu, and many hardier vegetables like broccoli, cauliflower, tomatoes, zucchini, carrots, and up to a point even iceberg salad, cucumbers, mushrooms (keep dry and airy if fresh, they dry out), as well as various pickles as snacks, if you're so inclined. With onions, potatoes, and eggs alone you can stuff your face for weeks without repeating a single dish. :)

I keep (vegan) crème fraîche, soy/rice/almond/oat drinks, and "cooking cream" around for weeks unrefrigerated as great milk and cream substitutes, but the milk-based products have a solid shelf life as well as long as they're unopened. This is perfectly viable for various creamy sauces or dips, and for cereals as a snack or breakfast option. With a nice oil or butter and a few seasonings you can whip up a surprising amount of simple meals, starting with classic pasta with a tomato sauce of your liking, to the typical trifecta of "carbs, meat, and veggies with optional sauce" that passes for an actual meal. You can easily build almost any kind of sauce you wish from stable ingredients to go with whatever, too.

There's a good bunch of great thai curry pastes around that go well with a handful of veggies and rice, and keep cooking effort to a minimum. If I'm particularly lazy, I boil a pot of potatoes and eat those straight with sour cream. Leftovers are due for the chippy treatment in a pan with onions and eggs, or just eaten cold as a snack with salt or leftover dip. Same goes for rice, the amount of stuff people throw atop their rice to chase it down is astonishing. Lao Gan Ma chili crisp is great, a straight sweet chili sauce works in a pinch, and if you're into chinese cooking anyway, you can throw almost anything in a pan, fry it up, and toss it to your rice with a generic "brown sauce" deal.

The biggest issue I see is fresh meat, though. That's quickly a serious hazard when kept at room temp, so I'd suggest to try reducing your meat intake as long as you're unable to store it properly, and otherwise cook the same day you buy. Truth be told, a lot of the vegan meat substitutes are surprisingly good by now, even though they're highly processed garbage and pretty expensive for what they are, but they keep unrefrigerated much longer and safer than the real deal. Don't expect a good steak, but anything "chicken" is nigh indistinguishable, IMHO.

All the other things do keep "fresh enough" at least for a couple of days, but you'll need to consider what you buy and when you are able to cook beforehand so things don't spoil, especially if you cannot buy fresh groceries more often than weekly for any reason.

TL;DR: For a generic meal, combine potatoes, rice, or pasta with a vegetable of your least distrust, optionally fresh meat if available, and a decent sauce. In a pinch, sauce + anything also works just fine, and sometimes even without sauce. Just don't take pictures for Insta when horking down a bowl of pasta with ketchup, we've all been there.