Alright, after a lot of tinkering, i have found the culprit.
I booted the Homatics Box into Android. After that i changed the display color depth to 8-bit 4:4:4. then, i restarted the box and plugged in the USB stick with a fresh 21.2 NG install on it. Suddenly, it started working, and I had a display.
After that, I removed CoreELEC USB stick again, changed the setting back to 10-bit 4:2:0, and rebooted again with the CoreELEC USB stick, and everything is working now. Happy days.
Now for my last question, which build should I use to start setting everything up?
Should I just use the most up to date NG build that can be downloaded from the CoreELEC site, or should I use a CPM build? wat is the most stable and works well with HDR10+ ( My tv doesnt have DV)
Thanks!