@bearer S3D is very picky about its ports. On Linux, it won't accept a "virtual" serial device like you'd create with socat. I can't try Windows but it might be worth a shot.
just occured to me using any esp8266-ish (board be it nodemcu/wemos d1 mini etc) you could probably combine Duet telnet with esplink firmware on the esp8266 to get you a hardware serial port that is networked to the Duet.
(but printing from the duets SD card is one of the bigger features)
((and with RC11 you could also get raw g-code from the PanelDue port to put into another esplink to avoid telnet))