I don't know anything about holograms, or about optics (I'm currently implementing code that takes advantage of OpenCV's camera calibration and don't even know some of the basics).

But I've read recently that some companies are trying to make better cameras (for phones etc) by making a meta-lens -- a single, flat lens with a highly detailed surface that can do the job that currently requires multiple curved lenses.

Do holograms have anything in common with surfaces like that?

If HOEs can direct light like several optical lenses combined into one, with a reflective enough surface, could holograms theoretically be used as some type of reflective (rather than refractive) lens like that for a smartphone (etc) camera? Can they reflect all wavelengths of visible light like you would need? Is anyone doing work in this area now?

There are even periscopic cameras in phones today - could we one day have a high quality camera in a slim device with one or two reflective lenses and no refractive element at all?

What's the difference like between something like LitiHolo and a machine required to make an HOE? What are the main relevant spec measures? I'm not sure if holograms have some equivalent of resolution, or similar.