Add chicken and 1 cup water to instant pot. Lock lid, and set valve to sealing. Program for manual-high and 12 minutes. When cook time ends, release pressure (QR). Remove and shred chicken; set aside. Drain water and return insert to instant pot.
Program for sauté. Add butter. When butter is melted, stir in 1/2 cup flour. Stir until smooth. Slowly stir in chicken broth. Stir and heat until thickened and bubbly.
Stir in frozen vegetables, shredded chicken, and salt and pepper.
In a separate bowl, mix 1 cup flour, baking powder, buttermilk powder, oil, milk, and salt. Stir until soft dough forms.
Drop dough by the spoonful onto the hot stew. Gently rest the lid on the instant pot (do not lock and do not seal). Let cook 20 minutes.