Heat olive oil in a skillet over medium-high heat. Add chicken chunks and cook until golden brown on all sides (about 3–4 minutes).
In a bowl, whisk together pineapple juice, brown sugar, and soy sauce until sugar dissolves.
Transfer browned chicken to a crock pot or baking dish. Pour sauce over the chicken, coating well.
Slow Cooker Method: Cover and cook on low for 6–8 hours until tender.
Baked Method: Cover with foil and bake at 350°F (175°C) for 35–40 minutes.
Spoon chicken and sauce over steamed rice. Garnish with green onions or sesame seeds if desired.