Select the saute function on the Instant Pot. While pot is heating, salt and pepper each side of your chicken thighs. Add oil to the hot pot, then crushed garlic. Cook for 1 minute, now add the chicken. Cook for 1 minute, now add the chicken. Sear chicken on each side for about 2 minutes (no need to cook all the way through).
Arrange the artichoke hearts, peppers, and olives around the chicken filling in the gaps on the bottom of the Instant Pot (if there are any). It's okay to let some of those veggies sit on top of the chicken. Top with sliced onion.
In a bowl, mix together chicken broth, vinegar, lemon, dried oregano, and dried thyme. Pour on top of the chicken/vegetable mixture. Secure the lid.
Select the manual function (this may be called "pressure" on certain versions of the Instant Pot). Adjust the time using +- button to 7 minutes (this will cook on high pressure for 7 minutes).
Once cooking is complete, use a quick release (natural release is also fine). Be sure to turn your valve down and release all steam before opening the lid.
Spoon out some of the juice into a small bowl once cooking is complete. Add 2 tbsp of arrowroot starch to the juice, whisk, and pour back into the Instant Pot. Allow the sauce to thicken for a few minutes before serving.
Serve over potatoes, rice, or cauflower rice. Top with fresh herbs, sprinkle with additional sea salt and pepper, and optional feta.