01 - Season the pork shoulder generously with salt, black pepper, smoked paprika, and garlic powder. Place the seasoned pork in a slow cooker or a heavy-bottomed pot. Add the chicken broth. Cook on low in a slow cooker for 6 to 8 hours, or simmer covered on the stovetop for 2 to 3 hours, until the pork is exceptionally tender. Remove the pork from the cooking liquid and shred it using two forks. Stir in 1 cup of BBQ sauce with the shredded pork and keep warm for assembly.
02 - Cook the rigatoni or penne pasta in a large pot filled with generously salted boiling water, following the package directions until al dente. Drain the pasta, reserving approximately 0.5 cup of the pasta water before discarding the rest.
03 - Submerge the thinly sliced yellow onion in buttermilk for a minimum of 20 minutes. While onions are soaking, prepare the flour coating. In a shallow dish, combine the all-purpose flour with paprika, salt, and black pepper. In a deep skillet, heat approximately 1 inch of vegetable oil to a temperature of 350°F (175°C). Remove the onions from the buttermilk, allowing any excess to drip off, and then dredge them thoroughly in the seasoned flour mixture, ensuring a light coating and shaking off any excess flour. Fry the coated onions in batches, maintaining the oil temperature, for 2 to 3 minutes per batch, or until they achieve a golden-brown, crispy texture. Remove the fried onions from the oil using a slotted spoon and drain them on paper towels.
04 - Combine the drained pasta with the prepared pulled pork mixture in a large bowl. Toss gently to coat. Add additional BBQ sauce as needed to reach your desired consistency. If the sauce appears too thick, gradually incorporate small amounts of the reserved pasta water until the desired sauce consistency is achieved. Serve the pasta and pork mixture in individual bowls, generously topping each portion with the prepared crispy onion strings. Garnish with fresh chopped parsley, if desired.