Pour chicken stock into Instant Pot, then set chicken inside on a trivet.
Pour ranch seasoning over the chicken, and set cream cheese on top.
Close Instant Pot and set to cook on high for 25-30 minutes.
Manually release pressure, then shred chicken.
Stir in bacon and white onions.
Spread out evenly in pot, then sprinkle cheddar cheese on top.
Replace the lid to trap remaining heat and melt the cheese.
Serve with sliced green onions on top.