Many times, when you won't get a greenscreen / chroma key working as it should and you don't have either time or sufficient light and equipment to fix it.
In this scenario, there is not so much that you can do.
But all is not lost, as I also accidentally Stumbledupon a good solution and I want to share it with you.
Try to find a good animated webcam overlay from Stream LabsOBS, etc. and adjust your webcam chroma key settings as much as you can without loosing your face and add that animated webcam overlay to front or behind your webcam.
This way your visible background after chroma key is used blends with overlay and your face cam/webcam feed is salvaged and your stream looks good.