Heat 1 Tbsp of oil in your Instant Pot (on saute) or in a pot on the stove on medium heat. Cut the sausages in 1/2 and the first batch to the pot. Brown on all sides, then remove from pan. Add the 2nd tbsp of oil and brown the 2nd batch.
While meat is browning, slice the peppers, onions, and mince the garlic.
Once all sausages are browned, set them all aside and add the peppers, onions, and garlic to the pot. Saute until they begin to soften, about 5 minutes.
Add sausages back to the pot, as well as tomato sauce, broth, red pepper flakes, Italian seasoning, and salt & pepper. Give everything a good stir to combine evenly.
Set timer to cook for 6 hours!