Heat 1 tablespoon of oil in a large deep skillet or Dutch oven over medium-high heat. Pat the chicken pieces dry and season with salt and pepper. Add to the skillet and sear until golden brown on all sides and mostly cooked through, about 5-7 minutes. Remove the chicken and set aside, leaving the drippings in the pan.

Reduce heat to medium. Add the minced garlic (and ginger, if using) to the pan and cook for 30 seconds until fragrant. Add the chopped bell peppers and sauté for 3-4 minutes until tender-crisp.

In a bowl, whisk together the reserved pineapple juice (about 1 cup), soy sauce, honey, and Dijon mustard.

Stir the rice into the skillet for 1 minute to toast lightly. Pour in the sauce mixture and stir well, scraping up any bits from the bottom. Bring to a gentle boil.

Return the chicken to the pot, distribute evenly, and add the drained pineapple chunks. Lower heat to low, cover tightly, and simmer for 20 minutes without peeking.

Remove from heat and let stand, covered, for 5-10 minutes. Fluff with a fork, garnish with green onions (and chili flakes if desired), and serve immediately.