Closest thing I can think of would be the tags system from DWM iirc or AwesomeWM or on Wayland RiverWM. They can be used like traditional workspaces but you can have a number of workspaces (tags) active at once. However, they are more merged and tiled together instead of overlayed on top which sounds like what the special workspace would do. At the time I used AwesomeWM I never really used the tags system to it’s full potential and only used it like traditional workspaces.