Organists would have to figure out some other strategy, though, since they do use both feet frequently. Still, if there's a button to push somewhere on the organ, that'd be at least easier than flipping a physical page.
For organists, these days pipe organs are usually outfit with a sequencer that allows the organist to program a list of registration changes (the combination of pipes/stops used) ahead of time; the organist then advances through the sequence of registrations, by bumping a bumper pedal with the side of their foot, or by pushing a toe stud pedal. Sometimes there are multiple toe stud pedals, which either allow for jumping straight to a specific combination, or for using the closest one as the program advance.
But yeah, even a button press or screen swipe should be easy enough to be useful in all but the most extreme cases (and in those cases a combination of memorization and automatic turning (e.g. tied to a metronome) could help further).