In a small bowl, stir together salt, paprika, chili powder, cumin, sugar, black pepper, and cayenne pepper.
Rub spice mixture all over Boston butt. Set aside.
Set InstantPot to saute; add olive oil. When oil is hot, add Boston butt.
Cook until browned on both sides, about 3 minutes per side.
Add chicken stock and garlic to InstantPot with pork.
Place top on InstantPot; twist to seal and lock. Turn Steam Release Valve to “sealing.” Set InstantPot to cook at High Pressure for 65 minutes.
After cooking is complete, let pressure release naturally (approximately 40 minutes). After
that, manually release the pressure by turning the Steam Release Valve to “venting.”
If desired, remove Boston butt from InstantPot; pour cooking juices into a fat separator. Skim off extra fat, and discard. Reserve remaining cooking juices.
Using two forks, shred meat, discarding fat and bones. Return shredded pork to InstantPot; stir together with reserved cooking juices. Season with additional salt, if desired. Serve with barbecue sauce, if desired.