Canon have released a camera driver for Windows, allowing select models to be used as a webcam - may be of use to some here.
I gave this a try today and unfortunately the Video Device In TOP shows the device correctly, but it just shows black image. We’ll have to look into it and see if we can tweak our DirectShow support, it is working in other apps like OBS, Zoom, etc so we should be able to fix it.
By the way, if you have an older Canon camera that is not on the ‘supported’ list, just try the closest camera. My 60D isn’t officially supported but worked fine by installing the utility for the 80D. (worked fine in other applications that is, not TD yet )
Canon have just released a Mac version - which works with TouchDesigner - download from the same link.