In a large skillet, heat the olive oil over medium heat. Add the diced onion and bell pepper, sautéing until they are softened, about 5 minutes.
Stir in the shredded chicken and pineapple chunks, mixing well.
In a small bowl, combine the soy sauce, brown sugar, garlic powder, ginger powder, salt, and pepper. Pour this mixture over the chicken and vegetables in the skillet.
In another small bowl, mix the cornstarch and water until smooth. Add this to the skillet, stirring constantly until the sauce thickens, about 2-3 minutes.
Remove from heat and serve over cooked rice or quinoa.