These are more or less "true" holographic elements, because they rely on wave optics and interference. But the pattern is fixed at manufacturing time, not varying with the image that's being displayed. And the image being displayed to each eye is still 2D, not 3D.
Basically, an HOE can act like a system of lenses and mirrors for collimating the image from each eye's display and making it appear at a comfortable viewing distance -- but is much smaller and lighter.
https://en.wikipedia.org/wiki/Holographic_optical_element
These are more or less "true" holographic elements, because they rely on wave optics and interference. But the pattern is fixed at manufacturing time, not varying with the image that's being displayed. And the image being displayed to each eye is still 2D, not 3D.
Basically, an HOE can act like a system of lenses and mirrors for collimating the image from each eye's display and making it appear at a comfortable viewing distance -- but is much smaller and lighter.