Can’t see it taking off in a big way.
I know everyone is different, but my fatigue is not just a “wanting to sit down” kind of fatigue, anyway. It’s mental as well as physical - I don’t see it being fixed just by having some sort of mechanical bum support.
If all I needed was the latter, I could use - dare I say it - a chair or perching stool.
I note the concept says it would be aimed at people who have to stand in one place for a long time. So how easy would it be to move about? Anything that makes the lower body heavier would be a hindrance, not a help.
Finally, it doesn’t look a world away from old-fashioned leg callipers. I think they are still in use today, for some of us who have trouble walking. But would anybody who doesn’t absolutely have to be eager to sign up for callipers? I wouldn’t. Desperate last resort only - otherwise, sit on a stool.
For those reasons, I’m out!