The point gaussian mapper has been updated to support 3D Gaussians, see https://gitlab.kitware.com/vtk/vtk/-/merge_requests/10662/diffs
Compute shaders support has been added in VTK too.
Everything is ready in VTK master, but sorting splats and computing view-dependent colors (optional, it works fine without it) has to be implemented by the application (ideally using a compute shader if there’s a large number of Gaussians).