Instant pot: Cut the pork into 3-4 large pieces. Add to the Instant Pot with remaining ingredients and toss until pork is well coated in the spices. Press the “Meat” setting and then press the “Pressure” button until the light on “High Pressure” turns on. Set the time to 30 minutes using the up and down arrows Cook and let the steam naturally release. Slow cooker: Add everything to the slow cooker and cook on low for 8-10 hours until the pork is fork tender. Pork tenderloin will cook in 3-4 hours.
For crispy carnitas, cover a baking sheet with foil. Turn the broiler on high. Spread the meat out on the baking sheet. Broil for 4-6 minutes until crispy. Toss with some of the cooking juice after broiling to add moisture back to the pork, for about 15 minutes. Carefully remove the lid and shred using two forks.