This is on a less than top end frame - but there is a visible twist. I made adjustments as best i could without the proper tools. He can shift cleanly in roughly 4 gears... after that, it just goes to poop.
get some clamps and you should be able to straighten it at least a little, I was able to do that with mine (on the MTB after sagamiko crash) while waiting for a new one. The best way to straighten it would be to get 2 matching bolts in a vice to simulate the frame mount, and one long bolt that would simulate derailleur and give it a few good smacks with a hammer, pliers or some wrench. if the hanger is from steel it should be just fine, if it's alu - as long as it's not cracked it will give in to some extent.
Steel and to some degree, Ti hanger or dropouts can be straightened. 6XXX Alloy hangers may be straightened maybe 1 or 2 times before they crack and break. 7XXX hangers or those that are T4 or higher are designed for much higher stiffness and may yield only once before sustaining cracks. So - if it bends, don't try to bend it back, it will just break. Carrying an emergency hanger is a good idea. Then even if someone else in the group has a failure , you can help them. As a side note - one of the most common issues I see on bikes is mis-alignment of the rear dropouts. Especially for wider range gearing and 11sp its critical the derailler travels in a horizontal plane with the cassette. I use a beefy VAR alignment rod to check this whenever I service a bike.