McNeel is developing a plug-in for Rhino using Blender Foundation's Cycles GPU render engine.
Cycles offers the same fucntionality like Keyshot but just faster and with a dramatically more mature and powerful material node system.
Rendering in Fusion with the build-in plug-in is incredible slow even on my 8 core MacPro.
Cycles with the GPU does the same image nearly in few seconds.
BTW Cycles engine is also open source.