Stud each onion quarter with a clove. Layer the bacon, sauerkraut, garlic, onion quarters, herb sprigs, bay leaves, pork chops, kielbasa, apples, and potatoes in the slow cooker in the order listed, then pour the wine and gin over the top. Cover the cooker and set it on LOW. Cook until the pork is falling off the bones and the potatoes are fork-tender, at least 6 and up to 8 hours.
Arrange the meats, potatoes, apples, onions, garlic, and sauerkraut on a large platter. Serve with pumpernickel rye bread, mustards, cornichons, and horseradish.