Cut pork into 4 pieces (as evenly as possible). Season with salt and pepper.
Pour oil into your Instant Pot and set to saute. When the oil is heated, add 2 pieces of the pork and sear until browned on all sides, using tongs to turn (approximately 1 minute on each side). Transfer to a clean plate. Repeat with the remaining 2 pieces of pork.
Turn off the saute setting by pressing "cancel". Return the 2 pieces of pork on the plate to the Instant Pot, along with any juices.
Pour the root beer over the pork.
Place the lid on your pressure cooker and lock. Steam release knob should be on "sealing". Cook on manual setting (high pressure) for 45 minutes. Allow the pressure to release naturally for 15 minutes, then quick release the remaining pressure.
Using tongs, carefully transfer the pork to a large bowl. Shred using 2 forks. Remove and discard any fat while shredding.
Pour sauce over pork and toss to coat evenly using tongs.