Thanks for @mal for hinting me about tombstones and reminding me about logcat. Here’s my log dump which consists of logcat output, journalctl output and /home/.android/tombstones/* crash dump files, feel free to have a look.
We’re quite far from my comfort zone, but I think this is linked to X10III losing audio which 1) did happen to me before I stopped and started app support, and 2) /system/bin/hw/android.hardware.audio.service shows up a lot in the tombstones.
I tested yesterday and Bluetooth audio works, as well as ringtone plays and even call audio works. I did multiple pulseaudio restarts in the initial process, however.