In a large bowl, combine flour, salt, pepper, garlic powder, and onion powder. Dredge the chicken pieces in the flour mixture, then dip them in the beaten egg.
Heat vegetable oil in a large skillet over medium-high heat. Fry the chicken pieces in batches until golden brown and cooked through, about 5-7 minutes. Remove and drain on paper towels.
In a separate saucepan, combine sugar, apple cider vinegar, ketchup, soy sauce, cornstarch, and water. Cook over medium heat, stirring until the sauce thickens, about 5 minutes.
Add the chopped bell pepper, pineapple chunks, and onion to the skillet with the chicken. Pour the sweet and sour sauce over the mixture and stir to combine. Cook for an additional 2-3 minutes until heated through.
Serve immediately over rice or noodles.