You need to install obs-v4l2sink.deb and v4l2loopback-dkms, then you can create a virtual webcam that you can choose in Zoom. I covered this in my live stream the other night (
https://www.youtube.com/watch?v=y5Zjm47ZFfA) at 38:50 in the saved recording. I am in the process of making a video of all the steps. Will try to post tomorrow.