Heat olive oil and onions until onions start to soften and become translucent, 2-3 minutes.
Add garlic, carrots and celery and saute for another minute.
Add whole chicken to Instant Pot, followed by water, soy sauce, 2 teaspoons of salt and several turns of freshly ground pepper.
Turn off Saute function, lock Instant Pot lid in place, make sure pressure valve is set to sealing and set Instant Pot to High Pressure for 20 minutes, via manual mode.
Instant Pot will take 15-20 minutes to come to pressure, then will countdown from 20 minutes.
After 20 minutes at high pressure, Instant Pot will beep and switch to keep warm mode.
Turn pressure release valve to Quick Release pressure. Do not leave unattended during Quick Pressure release. If any liquid starts to splatter, immediately close pressure valve using a wooden spoon. Wait 5 minutes and try and release pressure again.
Carefully open Instant Pot, keeping lid angled away from you to avoid very hot steam.
Remove whole chicken using kitchen tongs and set aside to shred.
Turn Instant Pot back to Saute function and let chicken broth come to a boil.
Stir in orzo and let cook for 8 minutes, or according to package directions.
While orzo is cooking, shred chicken into bite sized pieces, discarding bones and skin.
Once orzo cooked, stir in chicken meat, lemon juice and fresh parsley.
Adjust salt, pepper, and lemon juice to taste.