John Berkey and the Mechanical Planet

Yes, Lucas's walkers come from U.S. Steel's pictures of future walkers for snow use, which came from the General Electric walking truck.[1] The walking truck was really an exoskeleton; the human driver was doing all the control.

A big thing in the 1960s was operating in the Arctic, where the US and Canada were building chains of radar stations. Hence the U.S. Steel snow walker. The US Army had LeTorneau build several "overland trains", the largest being 170 meters long, with 54 powered wheels. [2] They look like something Lucas would have put in a movie. Worked fine, but were never deployed; heavy-lift helicopters became available.

The history of giant military ground vehicles is like that - they can be built, but are seldom useful. One of the lessons of tank design is that if it can't cross a standard bridge, ride on a standard railroad car, and drive on a standard road, it won't make it to the battle. In the 1940s and 1950s, all the players built prototype monster tanks, but nobody went beyond prototypes.

[1] https://www.youtube.com/watch?v=coNO9FpDb6E

[2] https://www.warhistoryonline.com/military-vehicle-news/the-g...