Add your olive oil and ground beef and cook for 2-3 minutes. Add your diced onion and continue cooking until most of pink in beef is gone and onions have softened slightly. Turn your Instant Pot off (important step so it can cool and doesn't display burn message later).
In a bowl whisk together your cheese soup and milk until creamy.
Add soup mixture.
Add all other ingredients (except your shredded cheese) into your pot and stir until mixed well.
Put your lid on and push the soup button, normal setting, for 10 minutes.
Do a slow release and lift lid carefully.
Stir in 1.5 c. shredded cheddar cheese until melted.
Serve with tortilla chips on the side, top with additional cheese and chives if desired.