I think your use of volumetric here is not a correct evaluation of the technology in the same way that you seem strident about calling out @AndreaJames for passing on a 3rd party use of the word holographic.
Volumetric has a very specific meaning in 3D and 2.5D visual production - the volume is the Z depth in X,Y,Z co-ordinates and the W depth in the U,V,W co-ordinates of non planar surfaces (UV the surface). Your lenticula work is essentially always 2d dependent on the Point of View of the subject - a nifty, yet sophisticated version of the old post cards that you tilt to get different images.
The image on @Faffenreffer sphere is essentially a 2D image that is mapped via a Mercator projection onto a sphere - no depth, no volume. Most often used inversely in planetariums.
Your use of parallax here seems non-standard and misleading in an interesting way. As this sphere is not reflecting light like any non luminous surface but projecting light from the LED’s you could possibly achieve a perception of parallax on a very large sphere or alternately film it on video with a wide aperture forcing the depth of field.
Ironically, to suggest the spherical persistence of vision model is “volumetric” is to almost suggest that it is holographic!
