Slice each pineapple in half lengthwise and hollow out the center by carefully cutting around the edges and scooping out the fruit, leaving about a 1/2-inch thick shell. Dice the scooped pineapple into bite-sized chunks and set aside. Reserve any pineapple juice collected for later use.

In a large skillet or wok over medium-high heat, add vegetable oil. Once hot, add the diced chicken breast pieces, season with salt and pepper, and stir-fry until browned and cooked through, about 5-7 minutes.

Reduce the heat to medium and add the garlic and ginger to the skillet, stir-frying for an additional minute until fragrant.

Add the diced red and green bell peppers to the skillet, continuing to stir-fry for another 3-4 minutes until the peppers are slightly tender.

Stir in the cooked rice, pineapple chunks, and reserved pineapple juice. Mix thoroughly with the chicken and vegetables.

Pour in the teriyaki sauce, soy sauce, and sesame oil, stirring to coat everything evenly. Cook for another 2-3 minutes to let the flavors meld and the sauce slightly thicken.

Once everything is well incorporated and heated through, scoop the chicken teriyaki mixture into each pineapple bowl evenly.

Garnish with sliced green onions and sesame seeds before serving.