Season the pork shoulder on all sides with salt, pepper, and thyme. Place it in the bottom of the slow cooker.
Scatter the sliced onion and minced garlic over and around the pork.
Add the quartered apples and shredded cabbage on top.
Pour the chicken broth and apple cider vinegar evenly over the ingredients.
Cover and cook on low for 8 hours until the pork shreds easily with a fork.
Remove the pork, shred it with two forks, and return it to the slow cooker. Stir everything together to combine.