If I recall their talk correctly, models are unions of SDFs, which get sampled into a point cloud, and each point gets splatted as another SDF primitive called a "fleck".

Ah thanks for the correction. The splat terminology they also use confused me.

I think SDFs is the data underneath, but baked into SDF voxel tiles at runtime and not always evaluating SDF shapes. The SDF tiles still get splatted.

At one point it used triangles for the large splats, and still compute shaders for the small ones due to quad overdraw. I'm not sure if the final version stuck with that or went all compute, but quad complexity is also why nanite does compute shaders for small triangles and traditional rasterization for the larger ones.