Add all the tomato sauce ingredients to your Instant Pot and mix well. The tomato paste should be dissolved into the tomato sauce if mixed enough. Place the lid on the Instant Pot (with the valve in the sealed position) and pressure cook on high for 5 minutes before quick releasing.
While the sauce is cooking, add the ground beef, bacon, garlic, egg and Worcestershire Sauce to a large mixing bowl and mix well with your hands.
Add the onion, dried oregano, dried basil, salt, pepper, Panko bread crumbs, milk and cheese to the ground beef mixture and mix well using your hands.
Roll meatballs into 1" balls (slightly larger than a golf ball).
Once the tomato sauce is done cooking, carefully add the meatballs to the sauce, making sure the meatballs are covered in the sauce. Place the lid on the Instant Pot (with the valve in the sealed position) and pressure cook on high for 5 minutes before quick releasing.
Insert a thermometer into the center of a meatball to confirm the temperature is a minimum of 145°F.
** OPTIONAL** For a thicker tomato sauce, transfer the meatballs to a large dish. Turn the Instant Pot on the saute setting and continue cook the sauce until your preferred consistency is reached. Taste and add extra seasonings if desired.
Enjoy immediately to ensure the juiciest meatballs.