I agree it'd be cool but it'd be tricky to design because naturally there's no source of food underground, and if there was, it'd change a fundamental part of the game for the players, we'd never have to return to the surface for food or supplies. We could just live entirely underground the entire game, breaking the game loop cycle.
You'd need a reason to still return to the surface for food. Maybe if they add a new food item that does grow underground but can't be harvested and taken long distances, only eaten at the growing source. Like it rots in a matter of minutes in your inventory if you dont eat it right away. Whether it be an animal or plant, doesn't really matter as long as it can't be a resupply for food while travelling. That way the village still has food, and the player can even eat and heal there, but it doesn't replace resupplying on the surface food to travel with. Even if players could replant the plant or lead and breed the animal, having to do that while travelling underground would be a hassle, a fair trade off for never needing to return to the surface.
So glowberries in the Lush Caves aren't food?