There exists resistive films in more rugged design but similar to what is used on some touch displays.

They can calculate the XY position where you press together the film.

The question here is how many concurrent steps you must be able to detect.

Do you need to detect the press of a foot or the setting down of the foot? Depending on floor and build height, it may be possible to use surface-mounted microphones to measure the vibrations and compute the intersection.