Going to have to, even if it’s just a stray, the level of injury is going to crank every panic dial to 11.

If your vet thinks the cat’s injury can be rehabbed and the cat is not so feral it will be impossible to care for, I recommend a dog crate for rehab care. Drape with a blanket and offer a box with one side cut off to hide in, room for small litterbox, food and water, not so big you can’t access him.