Instant Pot Lemongrass and Coconut Chicken

Name: Instant Pot Lemongrass and Coconut Chicken
Ingredients: 1 thick stalk fresh lemongrass (papery outer skins and rough bottom removed, trimmed to the bottom 5 inches); 4 cloves garlic (peeled and crushed); 1 thumb-size piece of ginger (peeled and roughly chopped); 2 tablespoons Red Boat fish sauce; 3 tablespoons coconut aminos; 1 teaspoon five spice powder; 1 cup full-fat coconut milk (+¼ cup optional); 10 drumsticks (skin removed (or 2 pounds boneless, skinless chicken thighs)); 1 teaspoon Diamond Crystal kosher salt; ½ teaspoon freshly ground black pepper; 1 teaspoon ghee or coconut oil; 1 large onion (peeled and thinly sliced); ¼ cup fresh cilantro (chopped); Juice from 1 lime (optional)