By default on Fedora, when you install the package
obs-studio you might not see the “Start virtual camera” button.
The reason is that OBS is expecting a v4l2loopback module to be loaded.
In order to do so, install the package “v4l2loopback”:
sudo dnf install v4l2loopback
Then insert the module:
sudo modprobe v4l2loopback
Now, start OBS Studio and you should see the “Start virtual camera” menu in the lower right corner.
The virtual camera allows you to inject pictures, logos, text, video streams (using VLC), etc. in your original webcam stream.
When in Zoom, Google Meet, Webex or others, simply choose the virtual camera as your video input device, and your audience should whatever you added in OBS Studio.