Has anyone figured out how to either compile libcec for windows on an ARM device, or found another solution to enable HDMI-CEC commands to be used with Windows 10 IoT?
As of recently, no. Reference link: https://www.raspberrypi.org/forums/viewtopic.php?f=105&t=111021
libcec's author is working on it, but there's no ETA. Here's the Github issue. Check the last few messages.
You could push your luck by exposing the CEC wires in an HDMI cable then bit-banging it with your GPIO port. Pin 13 if I'm not mistaken, red wire wrapped in foil together with white.That suggestion might be a little too extreme.
You could do it for science.