Add the brown sugar, paprika, chili powder, garlic powder, black pepper, and sea salt to a small bowl. Mix to combine.
Cover every part of the cubed pork in the spice rub.
Set Instant Pot to the sauté setting and add the oil. Once hot, add the pork and sear on each side, about 3 minutes per side. You will probably need to do this in 2-3 batches. Place pork on a clean plate after browned. Turn off the Instant Pot.
With a wooden spoon, scrape off the browned bits. You can add a tablespoon of water or two to help scrape up the browned bits if needed.
Whisk together 1 cup of the BBQ sauce, apple cider vinegar, and orange juice.
Set the Instant Pot to the High Pressure Cooking setting. Add the browned meat to the pressure cooker. Pour the BBQ sauce mixture over the top. Stir to make sure the pork is completely covered by the sauce.
Twist on the top and make sure the valve is at "sealed." Cook on high pressure for 55 minutes.
Let naturally release for 10 minutes, and then put the valve on quick release.
Turn pressure cooker off and carefully remove the top.
With a slotted spoon, remove the pork to a large bowl, leaving the liquid behind.
Either shred the pork or chop into smaller chunks.
Mix with the remaining 1/2 cup of BBQ sauce. Serve!