Check out Voxon [1]. From the specs and youtube videos it seems like it's working on the same principle (rotating LED screen). Fun fact, it was co-founded by none other than Ken Silverman (the creator of Build engine) [2]. They've been pushing commercialization of this technology for years now.
Also check out the company named "Light Field Displays" for stunning displays. Not exactly the same as volumetric. Arguably better in some ways. Definitely more expensive though.
Looking Glass displays (not the "hololuminescent" ones) solve many of the same things (multiple viewers, no glasses) while looking good, and in principle you could build a cube out of them, although the display can't be seen from the full 180 degrees.
[1] https://www.voxon.co/ [2] https://en.wikipedia.org/wiki/Ken_Silverman