Mix sesame oil, ginger, garlic, brown sugar, soy sauce, pineapple juice, and teriyaki sauce in a bowl.
Add chicken to a zip-top bag or dish, pour in marinade, and refrigerate for at least 2 hours or overnight.
Heat grill to medium-high.
Grill chicken 6–7 minutes per side, basting with reserved marinade. Cook until internal temp hits 165°F. Discard used marinade.
Grill pineapple rings for 2–3 minutes per side until caramelized.
Top grilled chicken with a pineapple ring, green onions, and sesame seeds. Serve warm.