Place a large skillet over medium-high heat. Add the oil and butter. When the butter is melted and the oil is hot, add the chicken, bell peppers and the whites of the scallions. Cook, stirring occasionally, until the chicken is browned and cooked through, about 5 minutes.
Meanwhile, make the sauce. Add the soy sauce, rice vinegar, cornstarch, ginger, chile paste, garlic and 2 tablespoons of the reserved pineapple juice to a mason jar. Secure the lid and shake until mixed thoroughly, then set aside.
Mix together the fried onions, peanuts, sesame seeds and chile-lime seasoning in a small bowl. Set aside.
When the chicken has cooked through, add the drained pineapple and stir to combine. Give the sauce a final shake and add it to the skillet. Allow the sauce to come to a boil and thicken, about 1 minute.
Serve over the rice, garnishing with the peanut mixture and reserved scallion greens.