Installing pulseaudio worked, likely due to an upgrade of some package.

I only did an upgrade of my packages, rebooted and then ran this command which ran through without removing any packages; it also installed "rtkit":

sudo apt-get install pulseaudio/buster-backports libpulse0/buster-backports libasound2-plugins.

I then rebooted and checked that pulseaudio is running.

However, the audio is still missing. It's still missing, without the volume buttons working, even after changing configs in daemon.conf and client.conf. How to enable the audio is a separate question.

Installing pulseaudio worked, likely due to an upgrade of some package.

I only did an upgrade of my packages, rebooted and then ran this command which ran through without removing any packages; it also installed "rtkit":

sudo apt-get install pulseaudio/buster-backports libpulse0/buster-backports libasound2-plugins.

I then rebooted and checked that pulseaudio is running.

However, the audio is still missing. It's still missing, without the volume buttons working, even after changing configs in daemon.conf and client.conf. How to enable the audio is a separate question.