Select the sauté function to heat the Instant Pot inner pot. When the display reads “Hot,†add the bacon pieces and sauté until crisp, approximately 5 minutes. Press Cancel to turn off the sauté function. Remove the bacon with a slotted spoon and place on a paper towel– lined plate. Set aside. Using a hot pad to lift out the inner pot, drain the bacon grease from the inner pot into a heat proof receptacle for disposal. Add the onion, potatoes, salt, pepper, crushed red pepper flakes, and chicken broth. Stir well. Secure the lid, ensuring the valve is turned to the Sealing position. Press the Pressure Cook button and set the time to 5 minutes. Once cooking is complete, allow the appliance to natural release for 10 minutes. After 10 minutes, turn the valve to the Venting position to release the pressure. When all the pressure is released, carefully remove the lid, add the sour cream, and stir well. Add the cheese one handful at a time, stirring until it is melted and fully incorporated. Divide evenly among 4 bowls, top with the reserved bacon and chives, and serve with bread.