Rebounders, aka mini-trampolines, are used for fitness:
https://www.google.com/search?q=rebounder

I think some of the sales pitches are overhyped in their appeal to a NASA study that was done on rebounding, but on the other hand, as a TOS person, this part of the study caught my eye:

In other words, the G-force is fairly evenly distributed throughout the body. So would the vertical G-force at the bottom pull the first rib down? That would be good. And if so, would it also pull the collar bone and shoulder girdle down? Because that would be bad. On the other hand, if the ribs stay down and the shoulder girdle can be brought up with a few shoulder shrugs, then we are back to good.

This is all highly speculative. I don't know if it would make my TOS worse, better or no different.

My other interest is being able to get aerobic exercise regardless of weather and time of day (which could also be accomplished by other means).

Anyway, who wants to go first and report back?