Coarsely shred pork, reserving juices. In a small bowl, crush half the pineapple with a fork., In a large nonstick skillet, heat oil over medium-high heat. Add whole pineapple chunks; cook until lightly browned, 2-3 minutes, turning occasionally. Remove from pan., Add enchilada sauce and crushed pineapple to same skillet; stir in pork and reserved juices. Cook over medium-high heat until liquid is evaporated, 4-6 minutes, stirring occasionally., Serve in tortillas with pineapple chunks, onion and cilantro. If desired, top with queso fresco and salsa, and serve with lime wedges.