Since I can remember, Guix's Audacity doesn't work with PulseAudio on my foreign distro (Debian).
Debian's Audacity does work correctly in this regard. In practice, this means that I cannot play or record audio in Audacity while any other application is using sound on the system. If I close or stop those other applications, then Audacity is able to select the 'sysdefault' output sound device and can start working. I found a few discussions about similar issues [0], and it seems that Audacity needs alsa-plugins in order to make this work. I tried installing Audacity along side alsa-plugins, alsa-plugins:pulseaudio, and pulseaudio, as well as building with them as dependencies, but it still didn't work. [0] e.g. https://forum.audacityteam.org/viewtopic.php?t=89278
