When raising a baby gacha, you don’t have to feed it anything. Just put it on wander and stay within render and it will actually feed itself. Also put it on a leash or pen. If you log off or leave render it will get sad and die. I learned it from a gacha breeder.
Gachas are essentially living lootboxes and resource farms. They will eat anything (including stone, wood, or fiber) and turb it into crystals which can drop a variety of resources including black Pearl's, organic polymer, or obsidian, among other things. They also have a rare chance to drop higher-tier crystals which turn into upgraded armor and tools