A better workaround was identified for the issue described in a previous edge blog post (here), and is provided in the device-purism-librem5 package version 1.23. This update conflicts with the workaround provided in that post.
Audio will once again stop working if device-purism-librem5 v1.23 is installed AND the workaround that modified /usr/share/alsa/ucm2/ucm.conf is applied. To restore audio, reverse the previous workaround by re-installing alsa-ucm-conf:
$ sudo apk fix -r alsa-ucm-conf
Also see: