Preheat your oven to 375°F (190°C).
Cut the tops off the bell peppers and remove the seeds and membranes. Place them upright in a baking dish.
In a large skillet, heat the olive oil over medium heat. Add the ground chicken and cook until browned, about 5-7 minutes.
Stir in the garlic powder, ginger powder, salt, and pepper. Cook for an additional minute.
Add the cooked rice, diced pineapple, and teriyaki sauce to the skillet. Mix well and cook for another 2-3 minutes until heated through.
Spoon the chicken and rice mixture into each bell pepper, packing it down gently.
Cover the baking dish with aluminum foil and bake for 25 minutes.
Remove the foil and bake for an additional 10 minutes, until the peppers are tender.
Garnish with chopped green onions and sesame seeds before serving.
