This indeed is an interesting development. I tried compiling on Linux and after sorting out a few complaints more and more of them emerged. Basically related to CMake not finding things. Therefore i am guessing things will hopefully improve on Linux in the future. If and when they do i guess we can evaluate if default Raytracing workbench should support CADRays in some way. If it makes sense to pack CADRays in binaries for all supported platforms. This would bring us closer to the goal of having a good rendering capabilities in FreeCAD by default. And for them to be available to non tech-savvy people. Currently this task is still reserved for POV-Ray and tech-savvy people using solutions such as Blender. Render workbench, being external, likely isn't as used and explored as it could be if it would be available by default.