Most military vehicles got them before the public did, power steering actually existed since 1876 but not much is actually known about him heres what wikipedia says:The first power steering system on an automobile was apparently installed in 1876 by a man with the surname of Fitts. Little else is known about him. The next power steering system was put on a Columbia 5-ton truck in 1903.[1]
Robert E. Twyford, a resident of Pittsburgh, Pennsylvania, USA, included a mechanical power steering mechanism as part of his patent (U.S. Patent 646,477) issued on April 3, 1900 for the first four wheel drive system.[2]
Francis W. Davis, an engineer of the truck division of Pierce Arrow began exploring how steering could be made easier, and in 1926 invented and demonstrated the first practical power steering system.[3][4][5] Davis moved to General Motors and refined the hydraulic-assisted power steering system, but the automaker calculated it would be too expensive to produce.[6] Davis then signed up with Bendix, a parts manufacturer for automakers. Military needs during World War II for easier steering on heavy vehicles boosted the need for power assistance on armored cars and tank-recovery vehicles for the British and American armies.[6]
Chrysler Corporation introduced the first commercially available passenger car power steering system on the 1951 Chrysler Imperial under the name "Hydraguide".[7] The Chrysler system was based on some of Davis' expired patents. General Motors introduced the 1952 Cadillac with a power steering system using the work Davis had done for the company almost twenty years earlier.[8]
Charles F. Hammond, an American, born in Detroit, filed several patents for improvements of power steering with the Canadian Intellectual Property Office in 1958.[9][10][11]
Most new vehicles now have power steering, owing to the trends toward front wheel drive, greater vehicle mass, and wider tires, which all increase the required steering effort. Heavier vehicles as common in some countries would be extremely difficult to maneuver at low speeds, while vehicles of lighter weight may not need power assisted steering at all.
But I would think the vehicles hitler drove didn't have power steering otherwise I think the steering wheels would be smaller, also I bet if Hitler was the one driving it would've gotten power assisted steering, because the Germans have always been one of those countries that were at the forefront of automotive innovations.
Best of luck