Can you fix severe hypokalemia just by eating a lot more potassium?

Usually no: The severe hypocalcemia is usually due to severe losses of potassium that exceeds ability of food to replace it. Otc pills are also not enough. Very imp to have lab f/u during replete on to avoid over or under shooting.

Low potassium: Depends upon the reason for low potassium. But yes the remedy includes intake of potassium that at least matches losses. Food potassium varies but is high in citrus, melon, tomato, potato, peaches, apricots, pomegranates, banana, greens, mango, and berries. You can avoid pills.

First, why K+ low?: I'd like to understand why you have severe hypokalemia to begin with. Do you have adrenal problems? Medication that causes loss of potassium? That is where I would start, because you can take potassium pills until the cows come home, but if you don't fix the reason for loss that doesn't solve the problem. Also consider that magnesium levels affect potassium. If mag is low you need that to raise K+