Place the onions and garlic in the slow cooker and then cover with the broth. Combine the brown sugar, chili powder, salt, cumin, and paprika in a small bowl. Pat the pork dry with paper towels. Rub the spice mixture all over the pork and place the meat on top of the onions and garlic. Cover and cook until the pork is tender, about 6 to 8 hours on high or 8 to 10 hours on low.

Turn off the slow cooker and remove the pork to a cutting board. Pour the onion mixture from the slow cooker in a strainer and return the solids to the slow cooker. You can strain the liquid into a bowl and save for later to make gravy or add some liquid back to the pulled pork if you prefer.

If the pork has a bone, remove and discard it. Using 2 forks, shred the meat, discarding any large pieces of fat. Return the shredded meat to the slow cooker, add the barbecue sauce and mix to combine.

Add the pulled pork to the buns and top with coleslaw.