In a bowl, combine the Sprite or 7 Up, soy sauce, calamansi or lemon juice, oyster sauce, fish sauce, crushed garlic, brown sugar, and salt. Mix well until the sugar has dissolved and the marinade is well blended.
Place the pork cubes in a large resealable plastic bag or a shallow dish. Pour the marinade over the pork, ensuring all the pieces are coated. Seal the bag or cover the dish and refrigerate for at least 3-4 hours, preferably overnight, to allow the flavors to meld and the pork to tenderize.
Thread the marinated pork cubes onto the soaked bamboo skewers. Make sure to tightly bunch the meat together (with little to no space in between) to prevent the skewers from burning and breaking during cooking.
Preheat your grill to high heat (about 450 F). If using a charcoal grill, make sure the coals are evenly heated and have turned white.
Place the skewers on the preheated grill and cook for about 8-10 minutes, turning occasionally, until the pork is cooked through and nicely charred on all sides.
When the pork is nearly done, quickly baste it with the basting sauce (very important!!!) and cook for another minute until the sauce is fully heated and looks caramelized on the meat.
Once cooked, remove the skewers from the grill and let them rest for a couple of minutes before serving.
Serve the Filipino Pork Barbecue Skewers hot with steamed rice, a side of atchara (pickled papaya), and a dipping sauce made of vinegar, soy sauce, and chopped chili for an authentic Filipino barbecue experience.