Turn on pot to the Sauté setting. Once the display reads HOT, add the sausage and onion and sauté until the sausage is completely cooked.
Add Italian seasoning, oregano, garlic powder, red pepper flakes, salt, and pepper and stir. If you are using green pepper or mushroom, add them here.
Add the broth and stir, scraping the bottom of the pot to deglaze by removing any browned bits stuck on the bottom of the pan. Cancel the Sauté function.
Add the pasta evenly over the mixture and DO NOT STIR.
Pour the pizza sauce over the pasta and to cover it completely and DO NOT STIR.
Lock the lid in place and move the valve to the Sealing position. Pressure Cook/Manual on HIGH pressure for 4 minutes (half of the boiling time as instructed on the box).
When finished cooking perform a Quick Release of the pressure by slowly moving the valve to the venting position. Do it slowly to prevent any splattering.
Carefully open the lid and stir in half of the cheese and all but 9 pieces of pepperoni. Stir in olives or cooked bacon if using.
Sprinkle the remaining Mozzarella cheese on top and then place the remaining pepperoni on top of the cheese. Close the lid and let the cheese melt.