Yeah, this seems like something that is cheap and low-tech that does close to the same thing. And a wheel in the heel allows for more control for the wearer with fewer things that can go wrong.
Heelys are fun — I got a pair when my kid got a pair — but they have a couple of drawbacks, they are very fussy about surface quality, not great with slopes, and impose a significant heel, which impacts posture and walking geometry (almost all my other shoes are zero drop, so this is very noticeable to me)