Add brown sugar, vinegar, ketchup, soy sauce, and 2 cups of pineapple juice to a large skillet over medium-high heat. Bring to a boil.
In a small bowl, mix cornstarch and the remaining ¼ cup pineapple juice together, whisking to get out all the lumps. Whisk into your skillet.
Add Meatballs and chopped peppers. Bring to a simmer.
Cover and cook for 8-10 minutes until the sauce has thickened and the meatballs are heated through.
Stir in pineapple chunks. Serve warm over rice. Top with green onion.