Hi @lbentes,
That should be possible, although you’d need to write some code to emulate a MAVLink vehicle so QGC can connect to it. It’s likely simpler to just make the script that’s controlling the lights provide a web page so you can set the level in your browser. Something like this may be helpful 
Actually controlling the lights can be done as discussed in your previous post (from last June).
As @FairweatherIT mentioned, you can avoid writing your own lights interfacing/control code by including a flight controller in the enclosure, at which point it’s effectively plug and play. Which option is cheaper/better for you depends on how much your time is worth, and potential further extensions you might want to get out of the system (there are tradeoffs to each approach).
To set up the video stream you can use gstreamer directly, or you can use it to set up a stream that starts when the RPi turns on, like we do in Companion / BlueOS. This comment describes the existing pipeline in Companion, along with a few different ways to receive the stream. Likely the easiest way to get a stream working though is to just use Companion or BlueOS directly.