In a small bowl, whisk together the soy sauce and miso until smooth, then whisk in the orange juice; set aside. On a 6-quart Instant Pot, select More/High Sauté. Add the oil and heat until shimmering. Add the onions and cook, stirring occasionally, until softened, 5 to 8 minutes. Add the mushrooms and garlic, then continue to cook, stirring occasionally, until the vegetables are lightly browned, about 5 minutes. Add the bourbon and cook, scraping up any browned bits, until most of the liquid has evaporated, 1 to 2 minutes. Stir in the miso mixture and 1 cup water, then nestle the chicken in an even layer, slightly overlapping the pieces, if needed.