Put 2-3 cups of water into your Instant Pot liner, along with the veggies, and then the whole chicken on top.
Close the IP lid, seal the valve, and press "Poultry." Bring the time up to 28 minutes. The IP will start on its own, taking about 5-10 minutes to come to pressure before counting down the 28 minutes of pressure cooking time.
Once the chicken is done pressure cooking, let the IP sit for 15 minutes to naturally release some of the pressure. After waiting 15 minutes, release the rest of the pressure from the valve, and transfer the whole chicken to a large dish or plate to de-bone. Strain the juices (called meat stock) and use those for any soups, stews, stir fry, or cooking veggies/rice in another time!
De-bone the whole chicken, and then shred the meat in a large bowl using 2 forks. Once the chicken is shredded, stir in the BBQ sauce, and then season with salt and pepper to your taste.