Mark 1 speaker drivers?

I’m looking to test some other voice assistant software on my Mark 1 hardware, so I flashed an SD card with the latest Raspbian, put it in the Mark 1, updated it, installed pulseaudio, and I can’t get the Mark 1’s speaker to work. I don’t hear any sound when playing an MP3 file.

“pactl list sinks short” only shows:
0 alsa_output.platform-soc_audio.analog-mono module-alsa-card.c s16le 1ch 44100Hz IDLE

Are certain drivers needed or something? I can’t seem to find source code or build scripts for the Mark 1 image, just the image itself.

I did check the various Mark 1 hardware/enclosure repos on the MycroftAI github, but didn’t find anything there about configuring the speaker.