I've been using gphoto2 and ffmpeg on linux to use my 6D MkII as a webcam. I did test it with my old old rebel XSI and it did work as well

here is the command

  sudo modprobe v4l2loopback exclusive_caps=1 max_buffers=2
  gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -an -threads 0 -r 24 -f v4l2 /dev/video2

I did wrap in a shell script to test if the module is already loaded.

Works on the 6D. Thank you!

I'm only getting ~4 fps, with substantial latency. Is that your experience?

Image quality on the first lens I had at hand (40mm f/2.8) blows my Logitech 920 away. Field of view on the 920 is equivalent to a ~26mm on full-frame.

Super excited to see if my slightly-broken EOS M will do the trick, too.

Awesome -- I'll have to give it a try :)!

I've been using a 6D mk.1 with the Windows version of the Canon Webcam Utility Beta for a couple weeks now. No issues with running it, so far.

6D Mk 1 works great with Canon Webcam Utility Beta on macOS! I'm using it now.