Add your bacon into the Instant Pot with the second half of your onions and continue to sauté. When the bacon has browned, thoroughly mix it in a bowl with the rice, beef, garlic, and the rest of the spices to create your filling.
Pour the marinara and chicken broth sauce into the Instant Pot, spoon the filling into your bell peppers, and place each one in the pot. Pressure cook the peppers for 10-12 minutes followed by a 5 minute natural release and finish with a quick release.