Basically searching for DoubleSight DS-10UT but bigger (13 inches seems ideal).
Requirements are following:
USB only, ideally signal and power in single cable. No HDMI/DVI/DSUB + USB, USB+Power is acceptable.
Touchscreen without additional cables
USB 2.0 compatible. USB 3 device backward compatible with 2, but at lower fps/resolution is still ok.
VESA (Adapter is acceptable)
Windows compatible.
Aside of DoubleSight, which is almost perfect aside of small size, I can't find device fitting all points. There is bunch of cool new devices from ASUS and similar, but touchscreen is rare and USB 3/USB C very common.
I am aware of USB graphic adapters and horrible ways of abusing tablets, but simplicity is preffered.