Place 2 pounds boneless, skinless chicken breasts, cut into 1-inch cubes, on cutting board. Season cubes of chicken on all sides with salt and freshly cracked black pepper to taste. Set cutting board aside.
Add ⅓ cup honey, ½ teaspoon salt, ⅓ cup low-sodium soy sauce, 3 cloves garlic, 1 teaspoon garlic powder, 2 tablespoons ketchup, and ½ teaspoon crushed red pepper flakes to medium mixing bowl. Whisk ingredients together until fully incorporated, then set bowl aside.
Set Instant Pot to Sauté mode. Add 2 tablespoons avocado oil and warm oil until hot and shimmering.
When oil is ready, add seasoned chicken pieces. Sauté chicken 5 minutes, stirring occasionally, until chicken pieces are just seared.
Pour honey garlic sauce into Instant Pot. Stir to incorporate chicken into sauce, scraping up any browned bits that may be stuck to bottom of pot.
Secure lid on Instant Pot with vent in Sealing position. Set Instant Pot to Manual High Pressure for 2 minutes. Instant Pot will pressurize, then 2-minute cook time will begin.
While Instant Pot cooks chicken, add 2 tablespoons cornstarch and 2 tablespoons warm water to small mixing bowl. Whisk ingredients together vigorously until fully combined. Set bowl aside.
When 2-minute cook time ends, carefully Quick Release pressure, then remove lid. Use caution as any escaping steam will be very hot.
Use slotted spoon to transfer chicken from Instant Pot to large bowl, keeping as much sauce in Instant Pot as possible.
Once all chicken has been removed, pour prepared cornstarch slurry into Instant Pot. Whisk vigorously until slurry is fully incorporated into honey garlic sauce.
Set Instant Pot to Sauté mode and bring mixture to boil. Boil sauce mixture 30 to 60 seconds or until sauce has thickened, then turn off Instant Pot.
Return cooked chicken to Instant Pot. Gently stir chicken into thickened sauce, making sure to coat chicken completely.
Once chicken is fully coated in sauce, portion chicken into serving bowls with cooked white rice (or cauliflower rice). Garnish with thinly sliced green onions and white sesame seeds if desired. Serve immediately.