Such slow movement has no cardiovascular benefit, so it’s pointless if you’re not trying to lose weight. Just use a sit/stand desk (and ideally, take breaks for exercise).
I still think these things should be rigged up to charge cell phones and whatnot. Lots of unharnessed energy released in exercise.
Not as much as you might think. The human body is incredibly efficient.
eg https://blog.directenergy.com/how-much-exercise-would-it-tak...
In most exercise machinery, there is an energy output that isn't being harnessed as much as it could be. Some stationary bikes and rowing machines use the person's pedaling or rowing to power the controls, so there is an example of where it is being used. But the majority of other pieces of equipment are not harnessing the energy output.
For example, every one of the pulley machines could have a magnetic shield around a segment of the (metallic) cable, which would produce a current both on the pull and on the release from the person exercising, without adding any noticeable tension.
Another example of where potentially harvestable energy isn't being used: although the chain on the rowing machine is often used to power the screen, the seat could also be used to generate electricity as it glides back and forth, using the same magnet concept.
I generally do 30-60 mins of active walking a day, usually in between active tasks.