In a small bowl, combine all spices: sea salt, black pepper, dried thyme, dried rosemary, paprika, onion and garlic powder.
Remove giblets from the chicken cavity if present. Pat dry the skin and inside with paper towels. Season chicken and chicken cavity with spicy mixture. Place half of a lemon and smashed garlic cloves into the cavity.
Place metal trivet into the instant pot and pour the water in. Add chicken breast side up and pressure cook for 24 minutes (for 3 pound chicken, add additional 8 minutes per each additional pound). When finished cooking, naturally release pressure for 15 minutes and make quick release of the remaining pressure.
Turn the oven to broil. Open the lid, remove the chicken and transfer it to the baking sheet lined with foil. Broil until the chicken is golden and crispy, about 5-7 minutes. Let rest 10 minutes before slicing.
While the chicken is broiling, prepare the gravy. Whisk xanthan gum with 3 tablespoons of cooking juices from the pot until well blended. Turn “saute” mode on the instant pot. Add 2 tablespoons of butter to the pot with juices and let melt. Add xanthan gum mixture and whisk until simmering. Turn the instant pot off.
Arrange chicken slices on a serving plate, pour the gravy over, and enjoy!