Ok. after some short digging, material overrides for #eevee are still out, but Zdepth on volumes are still in! If your computer can't render higher than 256 samples -;)
Just to give you an idea, with Zdepth and clipping compressed, this image is a default 64.. yes.. 64 sample render on the volume - silky smooth - meaning you really don't need huge samples to get rid of banding once you have a layered setup. I'll still make a video on it!