Return all browned pork to the Instant Pot. Add the chopped onion, minced garlic, orange juice, and lime juice.
Secure the lid with the valve set to sealing, and pressure cook on high for 60 minutes. Allow the pressure to release naturally for 15 minutes, then carefully open the lid.
Shred the pork using two forks, discarding any excess fat or liquid you don't want, and spread the meat on a foil-lined baking sheet. Place it under the broiler for 5-10 minutes.