Set Instant Pot to sauté mode. Add olive oil and light butter. When hot, brown chicken for 2-3 minutes per side. Remove and set aside.
Add garlic, cook 30 seconds until fragrant. Pour in chicken broth and lemon juice, scraping up any browned bits.
Return chicken to the pot. Seal the lid and set to high pressure for 10 minutes. When done, do a quick release of pressure.
Remove chicken. Stir in lemon zest and half and half, Mix arrowroot slurry and add to thicken (1-2 minutes).
Return the chicken to the sauce, spoon the sauce over the chicken, and garnish with parsley.