Cut the pork roast into sections to fit neatly in the bottom of the instant pot.
In the bowl of a blender or food processor, combine orange juice, pepper, salt, onion chunks, garlic, paprika, cumin, oregano, pepper, and jalapeños. Blend until a fairly uniform sauce forms.
Pour the blender sauce over the pork pieces in the instant pot.
Secure the lid of the instant pot and cook on the manual setting for approximately 30 minutes (additional time required for the pot to pressurize).
Carefully release the pressure from the instant pot and remove the lid.
Using two forks, shred the meat (it should fall apart easily).
Transfer the meat to a sheet pan and broil for 3-5 minutes until crisped and brown.
Serve as is or incorporate the meat and remaining juices from the instant pot.