Could I sub coconut milk or whole milk in for buttermilk? Would that impact the lightness/density of the bread?

Hi! If you're going to substitute coconut milk or whole milk for the buttermilk, I would suggest mixing it first with a teaspoon of white vinegar or lemon juice. The acid in the buttermilk reacts with baking soda, helping to leaven and aid the cornbread in rising. Hope this helps!

Hi. If you have whole milk on hand, add a tablespoon or white vinegar to a cup of milk and let it stand for a few minutes. That will produce a reasonable substitute for baking. But if you'll be grocery shopping anyway, pick up some buttermilk.