Pat the pork shoulder dry and rub all over with a mix of brown sugar, smoked paprika, garlic powder, onion powder, salt, black pepper, and optional chili powder.
Heat olive oil in a skillet over medium-high heat and sear the pork on all sides until golden brown, about 2 to 3 minutes per side, to lock in flavor (optional).
Place the pork into the crock pot.
In a bowl, combine barbecue sauce, ketchup, apple cider vinegar, and chicken broth. Pour this sauce mixture over the pork in the crock pot.
Cook on low for 8 hours or high for 4 to 5 hours until the pork shreds easily with a fork.
Remove the pork and shred with two forks. Return shredded pork to the crock pot and mix well with the sauce. Let soak for 15 to 20 minutes on warm.
Lightly toast the buns until golden.
Assemble sandwiches by piling pulled pork high on the toasted buns and drizzle with extra barbecue sauce or ketchup.
Serve immediately with optional potato fries and extra barbecue sauce for dipping.