Turn Instant Pot on "SAUTE". Add olive oil to the bottom of the pressure cooker. Add chicken and brown for about 3 minutes on each side.
Add chicken broth to the pot and scrape up all the bits on the bottom of the pan.
To the instant pot, add carrots, celery, onion, 2 tsp garlic salt, salt, pepper, and poultry seasoning. Secure the lid and set the pressure valve to "SEALING."
Select High Pressure with a cook time of 30 minutes.
When cook time ends, allow to naturally release for ten minutes, then do a quick release.
Remove the chicken from the pot and shred, while removing and discarding the skin and bones. Add the shredded chicken back to the pot.
Cut refrigerated biscuits into fourths and sprinkle with remaining 1 tsp garlic salt. In a small bowl, whisk cornstarch with cold milk. Pour into instant pot.
Turn the instant pot on "SAUTE" and add the biscuits to the mixture. Cook for about ten minutes, until dumplings have doubled in size, and sauce has thickened.
Video
Notes
If you’re planning on freezing this dish, I would do so BEFORE adding the dumplings. If you freeze with the dumplings they will get incredibly gummy.
I suggest you freeze without the biscuits. Place cooled chicken mixture into a ziploc freezer bag or freezer safe container. Freeze for up to 3 months.