Season pork roast with salt and ground black pepper on all sides.
Heat olive oil in a large skillet over medium-high heat. Cook roast in hot oil until browned, 3 to 5 minutes per side; transfer to a slow cooker.
Top roast with chopped onion, chile pepper, hot pepper sauce, chili powder, cayenne pepper, and garlic powder. Pour enough water into the slow cooker to come 1/3 the way up the sides of the roast.
Cook on High for 6 hours, adding more water if mixture becomes too dry. Reduce heat to Low and cook until meat is tender and falling apart, 2 to 4 hours more. Transfer roast to a bowl and shred meat using two forks. Return meat to slow cooker with 2 cups cooking liquid.