Preheat oven to 400°F and line a rimmed sheet pan with parchment paper.
Whisk together soy sauce, pineapple juice, brown sugar, vinegar, garlic, ginger, and olive oil to make the sauce.
Place chicken, pineapple, peppers, and onion on the sheet pan and pour the sauce over everything. Toss to coat evenly.
Spread the ingredients in a single layer for even roasting.
Bake for 20 minutes, stir, then bake another 10–15 minutes until chicken reaches 165°F and edges caramelize.
Garnish with green onions and sesame seeds before serving.