Combine all the ingredients for the all-purpose BBQ seasoning in a medium-sized mixing bowl and whisk to combine. Cut the boneless pork shoulder into 4 equal sized pieces and place in the slow cooker set on high. Toss the pork shoulder to completely coast the chunks using half of the all purpose BBQ seasoning (reserving the remaining half for when the meat is cooked). Add in the 1/2 cup of apple juice, and 2 tablespoons of apple cider vinegar to the slow cooker. Place the lid on and cook for 4 hours or until the internal temperature reaches 195-200 F and the pork shoulder is easily pulled apart. Once the pork reaches the appropriate temperature and tenderness, use 2 forks to pull the meat apart into bite-size chunks, allowing them to sit in the natural liquid from the meat that is in the pot. Mix in the remaining half of the all-purpose BBQ seasoning and serve with tangy vinegar Carolina-style BBQ sauce.