This. It's currently impossible, AFAICT, to use OBS to composite/produce a stream that is fed into video chat software like Zoom, Hangouts, Bluejeans, etc.
Using a plugin for OBS (Windows at least), you can absolutely output to a virtual camera, and use all of the compositing, filters, scenes etc in OBS. You don't get audio output, but you could probably solve that with a virtual audio cable. I do the video thing with Workchat and Bluejeans without issue, and just use my headset for audio.
I currently composite a view of my local harbour, my webcam, and a chroma-keyed nyancat gif, with a second scene for full-sized webcam. Works a charm, and actually uses less CPU that Chrome does when Chrome is routing that video to the VC.
