In a large bowl, combine the chicken pieces, sweet chili sauce, soy sauce, olive oil, garlic powder, onion powder, salt, and pepper. Mix well to ensure the chicken is evenly coated. Let marinate for at least 15 minutes for best flavor.
While the chicken is marinating, prepare the Brussels sprouts by placing them in a separate bowl. Drizzle with olive oil, and season with salt and pepper. Toss to coat evenly.
Preheat the air fryer to 400°F.
Once preheated, add the marinated chicken to the air fryer basket in a single layer. Cook for 10 minutes.
After 10 minutes, add the Brussels sprouts to the air fryer basket with the chicken. Cook for an additional 10-12 minutes, shaking the basket halfway through, until the chicken is cooked through and the Brussels sprouts are tender and slightly crispy.
Remove from the air fryer and let cool for a few minutes. If desired, sprinkle with sesame seeds and sliced green onions before serving.