Yes, you certainly can replace bone-in chicken with chicken breasts, if you prefer. I personally like the flavor of bone-in chicken, but boneless breasts are a great option as well - particularly if you want to cut down on cooking time. Use small-medium-sized (4-6 ounce) boneless chicken breasts, and skip the initial steps of searing the meat. Continue with the rest of the instructions and set the cooking time to 7 minutes. After the cooking cycle is complete, allow the Instant Pot to release pressure naturally for 5 minutes and then manually release pressure.