Place chicken in pressure cooker.
Whisk together soy sauce, water, honey, garlic, rice vinegar, ground ginger, and crushed red pepper flakes. Pour over chicken.
Place lid on pressure cooker, turn vent to seal. Press "pressure cook" and set timer to 35 minutes for frozen chicken, 30 minutes for thawed. When pressure cooker "beeps" to signal end of cooking time, allow a natural release (aka don't do anything) until the float valve sinks.
Remove lid, transfer chicken to a bowl and shred with two forks. Use a slotted spoon to remove any pieces of fat in the pressure cooker leftover from the chicken Set pressure cooker to "soup" setting. Once liquid comes to a boil, stir together corn starch and water and whisk into the sauce until thickened. Stir in sesame seeds.
Turn off pressure cooker, transfer shredded chicken back to the pressure cooker and stir to coat in the sauce. Garnish with chopped green onions and serve over steamed or fried rice.