Rinse the rice under cold running water in a colander until the water runs clear.
Place the rinsed rice, 2 cups water, and 1/2 teaspoon kosher salt in the Instant Pot inner pot. Secure the lid and set the valve to sealing.
Cook on Manual/High Pressure for 4 minutes, then allow a natural release for 10 minutes before carefully turning the valve to vent to release any remaining steam. Open the lid.
Fluff the rice with a fork and transfer it to a bowl. Rinse and dry the inner pot to remove any stuck bits, then return it to the Instant Pot.
Press Sauté and heat the 3 tablespoons vegetable oil. Add the diced chicken and chopped onion, season with salt and black pepper, and sauté until the chicken is cooked through, about 6–10 minutes.
Add the minced garlic and sauté for about 30 seconds, then stir in the frozen peas and carrots and cook for 2 minutes more.
Push the chicken and vegetables to one side of the pot. Pour the beaten eggs into the empty side and gently scramble until softly set, about 1–2 minutes, then fold the eggs into the chicken and vegetables.
Press Cancel. Add the cooked rice, 1 1/2 tablespoons soy sauce, sliced green onions, and 1 teaspoon toasted sesame oil to the pot. Stir thoroughly to combine and adjust seasoning to taste.
Serve warm, garnished with sesame seeds.