A couple of days have passed since my last post, and i must say, congrats @jock on your awesome work.
The build is running smoothly without any hiccups or other noteworthy bugs. After optimizing my Kivy app a bit more, the whole interface runs at a steady 60-120 fps.
I'm currently researching hardware accelerated video encoding to make the whole show complete (but, as you may have guessed, i know nothing about).
I've read about the 'Rockchip-linux' github repositories, but it seems like it's waaay out of my league, but i will try to make the best of it as i continue to learn.
HDMI audio didn't work right out of the box, you'll have to switch the default ALSA output (since the card gets recognized just fine)
Edit (or create) /etc/asound.conf and insert the following:
defaults.pcm.card 2
defaults.ctl.card 2
Reboot the box (or restart apps using audio output) and voilà. If that does not work, try searching for your 'HDMI' card using 'aplay --list-devices' and replace the number '2' with the one of your desired output.