Sorry for the confusion. For the moment I'm using it with original android firmware.
I tried the build suggested by user blustOne (above in this thread), booting from SD card, GPU has signal output but seems not to have HW acceleration for playback (it loads the file, but stutter/choppy playback). Also no sound through HDMI port.
I'm tring to first dump the entire firmware of the device. I don't want to get it bricked because of playing with it. Once I can dump it, I will try to play with the armbian variants, try to build my own, etc. I have never done this and I know I have a long way ahead reading and learning (and no much time), just I want to start with the backup. I will also try to debloat the android version.
I'm using it connecting a flash drive with videos, I connect it to internet as little as possible, it has many bloatware that I'm not sure of what thing it can cause in my private network. Probbaly i'm worring too much about it? ..