If you can’t hit 60fps at 1080p with Nanite enabled, you’re doing something wrong, buddy. I’ve got a fairly dense forest scene and it’s just shy of 60fps running on a 5700xt (this is a GPU with an architecture a generation older than current gen consoles) with a 1080p render target in the least performant area. If I disable Lumen it jumps up to ~90fps. Lumen is the performance killer in UE 5, not Nanite.
This is quite possibly the dumbest possible way to try to prove your point. You’re taking the final submitted frame data, with no knowledge of what the original assets are or what kind of rendering optimizations this game’s engine are doing to that data before submitting it to the GPU, and then sticking it in Unreal (also, as far as I can tell, you’re not putting the camera in the same place relative to the scene as wherever it was when you captured it. Also everything appears to be one material, which is obviously not how it rendered in the original. Also also your reconstruction is clearly non-manifold, implying some other advanced stuff going on under the hood in that engine).
If I dumped a Nanite frame and reconstructed it and put it back into Unreal again, guess what? It will render faster! Y’know why? Because the raster optimization that Nanite does dynamically is now precalculated and static. Rendering the whole test meaningless.