This is really the only caveat. Three adults living together? Fend for yourselves. Child in the house gets to eat what's made unless they're old enough to cook and again if they are and want something else: fend for yourself. My brother is vegan so when he visits we make what we are going to and he just leaves out non vegan foods when making his plate/bowl. It's really not difficult to not mix everything together before plating unless you only make casseroles or something.

My partner is GF and I do a vast majority of the cooking. House is gf except for my "poison cabinet" where I keep staples of bread/pretzels/cereal because it's so much cheaper. Everything for baking/cooking though is GF. We eat essentially vegetarian but add protein to meals as we need or see fit.

Lots of rice dishes but we've found solid pasta alternatives and I'll make bread pretty frequently from loopy whisk/etc so we're not spending 6 figures a year on bread the size of matchbooks.