Okay, I got it.

+ Entangle to grab the video from the Canon m50 over USB.

+ OBS to capture the video from Entangle.

+ v4l2-sink / v4l2loopback to send video feed to Jitsi.

https://entangle-photo.org/
https://github.com/umlaeute/v4l2loopback
https://github.com/CatxFish/obs-v4l2sink
https://obsproject.com/