Place chicken, teriyaki sauce, pineapple chunks, sesame oil, soy sauce, ginger, garlic and brown sugar in a Crock-Pot 6Qt Express Crock Multi-Cooker and stir to combine.
Put on lid and close pressure valve. Select Poultry setting for 15 minutes. Press Start/Stop. The pressure cooker will begin to heat and then start cooking.
Use the Natural Pressure Release Method after the cooking cycle is completed by waiting 10 minutes and then flick the tab on the Steam Release Valve to the "Release" position. Once all the steam is escaped and the Bobber Valve has dropped completely, open the lid.
In a small bowl, stir together reserved pineapple juice and cornstarch. Add to pressure cooker and stir to combine.
Select Brown/Saute and stir frequently for 5 to 7 minutes until the sauce thickens.
Place in serving bowls with rice and top with chopped green onions and sesame seeds if desired.