OBS Studio does an excellent job of mixing and streaming live to YouTube Live, Twitch, and other platforms but does not by default output as a webcam stream to Skype, Zoom, and other services that connect to a webcam. The instructions here are for Windows but there is also a link to an alternative app that should work on Linux (no MacOS unfortunately).
See How to Use OBS as a Webcam
With OBS-VirtualCam you can use OBS streaming effects with as a webcam for video services like Google Hangouts!