Combine the ketchup, vinegar, water, 2 Tbsp Sriracha, and ginger in a slow cooker and add the pork. Turn to coat. Cook on high for 6 hours and turn to low for 1-2 hours more, until meat is tender. Remove the pork from cooker. Remove bones. Stir in the remaining 1 Tbsp Sriracha to the sauce in the cooker. Add the pork back in to the cooker and shred, mixing the sauce and meat well. Serve as sandwiches or however you want to eat it.