> Displacement maps can closely approximate the geometric detail of having 1 triangle per pixel. All the work for displacement maps happens on a per-pixel basis inside a fragment shader (in simple terms, a little program that runs for each pixel of a triangle). You can wrap this displacement map over a single, large triangle and get the visual appearance of a much denser mesh.

I think you're wrong here... Can you provide an example of an engine where this is actually the case? To my knowledge (and I checked on Wikipedia [1] to make sure), a displacement map simply displaces VERTICES along their normals (so white color moves a maximum distance along normal, and black either doesn't move at all or moves maximum distance along the inverted normal - inwards). This means you need to heavily subdivide your geometry. Or you can remesh your geometry, with the simplest remeshing algorithms being just voxelizers - and that's what we see the OP doing - except in the place where all the 3D graphics complain on the limitation of voxelization, he hypes it as this new retro look he invented.

What seems to confirm my interpretation of all of this is how the OP describes this being done on the CPU, and - while he tries to downplay it - using rather decent hardware - I mean, Steam Deck is not exactly ancient hardware, and for an extremely simple scene with nothing else going on, he's happy being above 60 FPS on 800p resolution!

[1] https://en.wikipedia.org/wiki/Displacement_mapping