I never saw him eat or drink anything prior to being discovered by the mom of the family he moves in with. As far as I remember. So, I figured he probably wasn’t fully “human” yet and was maybe hollow? So it all just sloshes down into the feet to be mushed out through pores? Or he might have something that makes him run internally that’s hot enough to evaporate food and drink upon impact. Either way, I feel like these are still plausible because I do remember it showed him at the end making “snow” from the ice sculptures and he didn’t age like Wynona’s character did. He’s immortal it seems. So I don’t think he pees or poops at all. I do think it’s weird he threw up from a hangover though.