Yep, I would give it a go. I would chuck in some onion, garlic, stock cubes, and whatever veggie you want (carrots and celery are always a good base). Thyme and/or sage work well with pork, but if you wanted to spice it up you could fry in some cajun-style spices at the start and add tomato paste, capsicum, sweet potato for some sweetness. If you want it a bit heartier, add in some carb like pearl barley, pasta or canellinni beans. I love the old story about the "stone soup" - so I don't think you can really go wrong making soup out of leftovers.