I've finally got the tachyon running and the screen to be used will be a TV ( 58” Samsung NU7100 if context matters for the question): can I get audio via hdmi? So far settings says “dummy output” and I can't really see any way of changing that, thanks!
I managed to get audio mostly working by getting rid of the buggy installation of pulseaudio, and switching over to pipewire+wireplumber (available from debian PPAs). Bluetooth A2DP audio works perfectly with headless, but in the desktop image there are some clashes between GDM and the user pipewire daemon that I gave up on trying to solve. I don’t think audio will get any better on 20.04 – Ubuntu switched to from pulseaudio to pipewire in later releases, so there’s little incentive to fix the problems.
ChatGPT 5 should be able to walk you through the change based on what I wrote above (make sure to also mention that this is a Particle Tachyon and that you are currently limited to 20.04)