WI Igor Sikorsky manufactured a helicopter before WW2?
Granted, it would be small and short-ranged and maintenance intensive, barely able to lift two men and their lunch for two or three hours. IOW not much more than a spotter aircraft for artillery forward observation officers.
How would helicopter spotters have affected U-boats?
How would helicopter med-evac change casualty rates on WW2 battlefields?
How would spotters improve naval gunnery accuracy when re-taking Pacific Islands?