Not trying to sound cold here, but there’s not much anyone can do for that injured bird. It’s admirable to hear about your desire to help it. I would feel the same. The bird probably won’t last long as it was probably injured after an encounter with another animal. But it’s the reality of nature taking its course. Left alone outside it will become fodder for other creatures.
I’m not a vet, but it looks to me like the injury sustained may be life threatening anyway. If not life threatening, it will likely not be able to feed itself which means the end for the bird is just a matter of time.
Some folks would hasten to put the bird out of its misery. But I certainly would never try and tell anyone what to do in that regard. 😢