In theory the wavefront emulator is the simplest display - all of the "pixels" are rendered in your brain so you don't have to build an actual "display" HOWEVE

In theory the wavefront emulator is the simplest display - all of the "pixels" are rendered in your brain so you don't have to build an actual "display" HOWEVER if someone can get the input -> photon production pipeline to be less than ~10ms, then that does solve a lot of the rendering issues, however it doesn't solve all of the other long term problems that come with that amount of hardware - including weight and complexity. That said, there's a lot of known-unknowns that need to be solved, for example I don't have a solution for micropiezo resonance issues that I'm sure will crop up.