This app allows you to take photos and videos by using both cameras at the same time, overlaying the image from the front camera on the rear camera.

The function to use the front and rear cameras simultaneously requires a device with Android 11 installed, but it may not be available on some devices.

In that case, please try it on a relatively recent device (a device with Android 11 installed as the initial setting).

You can change the size of the overlaid image, change its display position, and switch the camera image.
You can also do this while recording a video.

Also, if supported, you can record videos in 10-bit HDR. Please enable it from the settings.

This app is open source.
https://github.com/takusan23/KomaDroid