I recently released a small new macOS mostly because I wanted to use it at work. The issue it tries to solve is that sometimes I want to quickly show something during a video call, but I don’t want to go through the “Share Screen” overhead. Depending on the situation this requires asking for permission, “can you see my screen?” or something not working. Emyn installs a virtual camera on macOS which just replicates your webcam feed. It then has the option of replacing the background of your feed with the contents of one or more of your macOS windows. Beyond that, you an also scale down your video feed - so that more of the window is visible - and control the window right from within Emyn (via a large blue mouse pointer).
I find this very useful, as it allows me to structure some of my meetings by also having lightweight slides to guide my explanations. For fun, I also added a NTSC effect and a Confetti effect to the app. Also, transcription because why not.
You can find Emyn on Github, here. It still has the one or other bug, but I’ve used it multiple times and it works great.