I was wondering if there are any window mounted split air conditioners in US market or anywhere else - One in which compressor and radiator hang out of the window and only evaporator is inside the room. I was able to pull up many patents from as early as 1938 with same idea but don't think a commercial product exist. Any thoughts why it could be so?
Yes, there are "saddle" or "hybrid" units which are basically as you describe. See, for example, the SoleusAir WS3-06E-201.