As a person who grew up on kraut made by my parents from our own home-grown cabbage, I agree most canned kraut doesn’t come very close to "real" kraut. Onions and garlic could be possible additions, as well as a "bitter" spice like juniper berries or caraway seeds, all if used in moderation so there is just a hint of a flavor change, but I would never even consider adding a "sweet" spice like cloves.