In theory it should be possible. It could be like Photoshop and just cutting out your face and making the rest Transparent (though of course it won't follow the face, just the shape).
But that would need it to be allowed by OBS.
I doubt it can easily be done with this OBS, but with OBS-Redux, it should probably be quite easy, if it's user-friendly as modular.
(That being said, i don't know how to do it, just stating examples here*)
