Set your Instant Pot to the saute function and heat the olive oil.
Add the lean ground beef and cook until browned, breaking it apart with a spoon.
Add the diced onions, celery, and green pepper to the pot and saute until the vegetables are softened.
Stir in the minced garlic and cook for another minute until fragrant.
Add the tomato soup, diced tomatoes with their juice, mushrooms, kidney beans, chili powder, oregano, salt, black pepper, and sugar.
Stir all ingredients thoroughly to combine.
Secure the lid and set the pressure valve to sealing.
Cook on high pressure for 15 minutes.
Perform a natural pressure release for 10 minutes before switching to a quick release for any remaining pressure.
Stir the chili well before serving hot.