The gelatin is entirely from the wings in this case but I’m not above adding it if it seems like texture will improve. Kenji Lopez-Alt wrote about adding gelatin to improve pan sauces a few years back (and spoke about it recently on his now daily POV cooking videos) but I think that’s just one application.
One of the advantages of gelatin is that it’s thermoreversible (which is just a ten dollar way of saying gelatin will remelt with heat). This is contrast to things like starch in gravy which gets pasty after refrigerating. I’ve been trying to use this feature of gelatin in applications like below where the gravy for a shepherd’s pie is a mix of starch and gelatin. Not only will it have good texture even after reheating from the fridge, it also makes certain aspects of cooking easier.
Sorry for the symposium on starch and gelatin, it’s a bit of a hobby horse of mine at the moment. I’m under no illusion I invented these uses- starch and gelatin are some of the most traditional hydrocolloids there are, I just think there are some uses that haven’t 100% entered common knowledge.