In your Instant Pot, or in a saute pan over medium heat on the stovetop, heat the oil until shimmering and brown the pork on all sides, working in batches if needed. (Transfer the pork to the Instant Pot if you browned it on the stovetop.).
Add all the remaining ingredients. Place the lid on the pot, turn the pot to the "sealing" position, and select Manual mode and set the time for 20 minutes. Once it finishes cooking after 20 minutes, allow the Instant Pot to manually release for 20 minutes.
Take off the lid (if the steam valve hasn’t dropped, make sure you move the steam value away from "Sealing"). Let the pork cool slightly, then use two forks to shred the meat. It may look like you have way too much liquid, but it will absorb it after you shred the pork.
Once shredded, use the pork however you like. I like to toast a few tortillas and top them with the pork, pineapple salsa, fresh cilantro, and a squeeze of fresh lime juice. Carnitas make a great salad topping, and are also excellent mixed into rice, in a sandwich (try it! trust me!), or reheated until crispy and served with eggs and hot sauce and avocado.
Note: If the pork is too liquid-y even after shredding and sitting, transfer it to a large pan and cook it on the stovetop until some of liquid evaporates. This is also an excellent way to get the meat golden and crispy (you can also spread it on a sheet pan and broil it for a minute or two)—for tacos and salads, I like to take this extra step to get those crunchy edges.