Rinse and drain rice, then cook according to package directions.
Whisk together orange juice, marmalade, soy sauce, vinegar, ginger, honey, garlic, chili garlic sauce, orange zest, ½ teaspoon salt and ¼ teaspoon pepper; set aside.
Using sauté function, heat oil in Instant pot until shimmering. Add chicken and cook, stirring frequently, until opaque on all sides, about 3 minutes.
Stir in orange sauce mixture. Lock lid in place and close pressure release valve. Select high pressure cook function and cook for 4 minutes.
Turn off instant pot and quick release. Carefully unlock and remove lid, allowing steam to escape away from you.
Using a slotted spoon, transfer chicken to a bowl. Set pot to sauté function and simmer sauce 5 minutes.
Meanwhile, whisk together cornstarch and ¼ cup water. Stir cornstarch slurry into sauce, then add broccoli and cook until sauce is thickened and broccoli is crisp-tender, about 4 minutes.
Turn off Instant Pot, add reserved chicken and sesame oil to pot and stir to combine; season with salt and pepper to taste.
Serve orange chicken and broccoli with cooked rice and top with green onions and scallions.