Prepare the Meatball Mixture: In a large mixing bowl, combine the ground pork, minced garlic, onion powder, grated onion, barbecue sauce, salt and black pepper. Mix well until all ingredients are evenly incorporated.
Form the Meatballs: Using your hands, shape the pork mixture into small meatballs, about 1 to 1.5 inches in diameter. Set aside.
Sauté the Meatballs: Turn on the Instant Pot to the "Sauté" mode and add the oil to the inner pot. Once hot, carefully place the meatballs in the pot, working in batches if necessary to avoid overcrowding.
Sear the meatballs on all sides until browned, about 2-3 minutes per side. Remove the meatballs from the pot and set aside.
Prepare the Sauce: In the same Instant Pot, add the diced red bell pepper and sauté for 2-3 minutes until slightly softened. Add the soy sauce and pineapple chunks to the pot, stirring to combine.
Pressure Cook: Return the meatballs to the Instant Pot, nestling them into the sauce and pineapple mixture. Pour the water over the meatballs. Secure the lid of the Instant Pot and set the valve to the sealing position. Select the "Manual" or "Pressure Cook" setting and cook on high pressure for 8 minutes.
Natural Release: Once the cooking time is complete, allow the Instant Pot to naturally release pressure for 5 minutes. Then, carefully perform a quick release to release any remaining pressure.
Serve: Carefully open the lid of the Instant Pot and transfer the Hawaiian pork meatballs to a serving dish. Serve hot, garnished with chopped fresh cilantro or green onions if desired. Enjoy your flavorful Hawaiian-inspired meal!