Guests can join the Greenroom with a camera/microphone and share their screen at the same time:
Join the Green Room with a Camera and Microphone
Once connected, click Share Screen to share your desktop, application window, or browser tab.
Your screenshare feed will appear in the gallery view for you and all other participants.
Sharing your screen: What you need to know
The ability to stream a camera and share screen at the same time is only available with Scenes. Hosts using Performance Mode will not see the Screenshare feed.
Your microphone is included only with your camera feed, so the Screenshare will not contain any audio. That way the host can include both your Camera and Screenshare in the same scene without getting double audio or echo.
As a guest, both your Camera and Screenshare feeds will be recorded in the cloud, however the Record Me option records only your camera feed.