Preheat oven to 400°F and line a baking sheet with parchment paper.

In a bowl, combine ground beef, breadcrumbs, egg, garlic powder, onion powder, salt, and pepper. Mix gently and roll into 1-inch meatballs (about 20 to 24 meatballs).

Chill the rolled meatballs in the refrigerator for 10 to 15 minutes to help them hold their shape.

Heat olive oil in a skillet over medium heat. Brown meatballs in batches, avoiding overcrowding.

Transfer browned meatballs to the prepared baking sheet and bake for 10 to 12 minutes until cooked through (internal temperature 160°F).

In a saucepan, combine ketchup, brown sugar, rice vinegar, soy sauce, pineapple chunks with juice, bell peppers, water, and cornstarch.

Simmer the sauce over medium heat, stirring frequently, until thickened (about 5 to 7 minutes).

Add cooked meatballs to the sauce and toss gently to coat each one completely.

Serve hot over rice or noodles, garnished with scallions or sesame seeds if desired.