dslrdashboard.info

Check that you Android device does not change the wireless AP automatically if it senses that there is no internet connection available on current one.
Also check that your Android device does not go into sleep as it can automatically kill qDslrDashboard.

The Sony a7 IV wireless connection is not yet supported.
Only the Sony cameras that support the 'Smart remote control' application will work with wireless connection.

No, the Sony a7 IV will not yet work fully. I began working on it but without a proper documentation and a physical device it is slow and hard to make a proper implementation.

Yes, the fully functional free desktop versions for Windows, Linux, macOS available at: https://dslrdashboard.info/downloads/

Is your camera set to single capture mode?
Check the 'Use Canon Local storage' option in qDslrDashboard settings, try disabling it before you connect the camera.

Will check if I can use an older OpenCV version, but not sure if it will work.

Android 4.4.2 should work.

To long USB cable can create connection issues (voltage drop).

The Qt libraries where built with Raspbian OS, so it will only work with it.

Buster build will not work Bullseye.
I will first need to manage and build it for Bullseye.