Comment by franga2000 a day ago
I'm not sure since I don't have any Canon gear, but it's very likely that the app just uses the PTP protocol, which is an old but stil common standard. The main ioen source implementation is libgphoto2 and there's an OBS Studio plugin to use it as a camera source, after which you can use its built-in virtual webcam mode to use it as a webcam.
Worth a try compiling a custom version after adding to https://github.com/knro/libgphoto2/blob/master/camlibs/canon... Hopefully it's as easy as that.
I'm able to pipe gphoto2 frames to a pipewire sink or v4l2 device and it works great for making my Canon EOS 250D into a webcam.
Newer Nikon and apparently also some Sony cameras simply support USB UVC ("the webcam protocol"), which makes this pure plug and play, but apparently Canon doesn't. For older cameras there's a Nikon webcam utility or something like that, which does exactly what you suggest: grab preview frames via PTP and stuff them into a video source. Or you get an HDMI/USB dongle for 10$.
Canon G5 X mark 2 does not seem to be supported by gphoto:
http://www.gphoto.org/proj/libgphoto2/support.php