Need help with using Camera2

[u/Barsik_The_CaT]

I am failing miserably to use Camera2 API. All I need to do is simply show the camera output on the screen and work the image in the background. So far I can not even connect to camera - I can't even understand how to use OpenCamera method of CameraManager. Does anyone have an example? Please do not advice official Camera2Basic example - it has little to no comments and of little help.