In a large bowl, combine ground beef, breadcrumbs, eggs, garlic powder, salt, and pepper. Mix until just combined; shape mixture into golf ball-sized meatballs.

Preheat your air fryer to 380°F and cook the meatballs for 10 minutes, shaking halfway through. Oven method: bake at 400°F for 20-25 minutes until golden and cooked through.

In a separate bowl, whisk together rice vinegar, brown sugar, chicken broth, ketchup, tomato paste, pineapple juice, and cornstarch until well blended.

Heat vegetable oil in a large pan over medium-high heat. Add diced onions and bell peppers, sautéing for 1 minute. Add garlic and cook for an additional 30 seconds.

Pour sauce into the vegetable mixture, stirring continuously. Let simmer for 2-3 minutes until thickened.

Gently add cooked meatballs and pineapple chunks to the pan, tossing to coat. Heat everything together for 2 minutes.

Serve over fluffy white rice or egg noodles, garnishing with green onions or sesame seeds.