Yes, cpufrequtils has been removed upstream. It's not anymore in Debian stable. https://packages.debian.org/search?searchon=names&keywords=cpufrequtils

Hey, I think I'm impacted by the same issue. I've replaced the original fan of the HC4 with a Noctua NF-A4x10 5V PWM earlier this year. It was working as expected, but since couple weeks the fan is at 100% speed continuously, which is loud. It sounds like it's a software upgrade that broke the PWM control, but no idea which one. I've done part of the same testing you mentioned but didn't managed to find a fix neither. I'm probably even more beginner than you, so I don't think I can help much unfortunately. How can we get more eyes on this issue? Did you post on Odroid Forum?

OK, so I installed the latest Debian/Trixie + Cinnamon + vendor kernel available and audio is working. The name of the cards and mixers are different though: speaker-test worked both by specifying the mixer (... -D plughw:CARD=rockchiphdmi0,DEV=0) or through PulseAudio's ALSA emulation after setting the default sink to the rockchiphdmi0 card. The list of audio cards is different in the vendor kernel than what's available OOB with the edge kernel, so I'm not sure if the configuration is comparable. But the audio port/cable combo seems to be fine so there's that..

Yes, exactly.

Oh are you saying that the Tuxedo v1.0.30 package works with the latest 6.12.44 headers? I did not try moving ahead to the latest as I didn't see an option to swap to that kernel in armbian-config (only to go back to 6.12.32). My current kernel is 6.12.41 (default install). I assume I can manually update via: sudo apt-get update && apt upgrade -y and then install the headers afterwards.