You’re just using the app to display your webcam’s live feed. This app would also let you change the background of your video feed, I think (please test for yourself).
And you could make use of the fun features of Snapchat's Snap Camera (though I've heard this app has security risks, so download at your own risk). You can also go semi-pro and download VLC Player (a free, well-respected, open-source video player), set it to capture device then set the window to always on top.
On Chrome OS (Chromebooks), use the included Camera app.
On macOS, open QuickTime Player and click File > New Movie Recording. If your camera feed comes through flipped horizontally, here's a way to troubleshoot that. On Windows, you can use the Camera app (open the Start menu and search Camera).