Cut the pork loin, pineapple, bell pepper, and red onion into uniform 1-inch cubes.
In a small bowl, whisk together the avocado oil, sea salt, black pepper, and garlic powder.
Toss the pork cubes in the oil and spice mixture until evenly coated.
Thread the pork, pineapple, pepper, and onion alternately onto wooden or metal skewers.
Preheat a grill or grill pan to medium-high heat and lightly grease the grates.
Grill the skewers for 8 to 10 minutes, turning every few minutes to ensure the pork is cooked through and the edges are crispy.
During the final 2 minutes of grilling, brush the BBQ sauce generously over all sides of the skewers until the sauce is bubbly and slightly charred.
Remove from heat and let rest for 2 minutes before serving.