Set Instant Pot to sauté and give it about 8-10 minutes to preheat. Add the oil and let it heat up.
Add the vegetables and saute until soft, about 4-5 minutes. Add the garlic and continue cooking for another minute. Turn off the Instant Pot and transfer the sauteed vegetables into a bowl.
Hydrate the bread pieces with milk and add to the vegetables. Add the meats, eggs, salt, peppers, ancho chile, and 1/3 cup of the BBQ sauce and mix well.
Wet your hands and shape the meat into a loaf positioned across a 12"x7" aluminum foil sling brushed with oil. Place on the steamer rack. Pour 1/2 a cup of water into the Instant Pot, then transfer the meat with the rack into the cooker.
Cover the pressure cooker and make sure the pressure valve is sealed. Set for MANUAL, HIGH pressure for 15 minutes cook time.
Turn off the Instant Pot and quick-release pressure. Carefully remove the lid, allowing steam to escape away from you.
Using the sling, remove the cooked meatloaf from the cooker to a serving platter. Cover with a foil tent and let rest for 5 minutes.
After 5 minutes have passed, glaze the meatloaf with the rest of the BBQ sauce, slice and serve with your favorite side dish.