How to make audio devices available with guix shell --container

[Elias Kueny]

Hello,

I'm trying to run an online videoconferencing tool in chromium in a guix shell 
with a container, so I expose my system as little as possible. All is well 
without the --container option, but I'm not sure what to expose to make it work 
in the container too.

I'm on guix system. I'm starting the software with: `guix shell --container -N -P 
--no-cwd --preserve='^DISPLAY$' --preserve='^XAUTHORITY$' --share=$XAUTHORITY 
--share=/dev/video0 ungoogled-chromium -- chromium --app="https://meet.jit.si"`.

`--preserve='^DISPLAY$' --preserve='^XAUTHORITY$' --share=$XAUTHORITY` lets 
chromium open an X window and share the scren.
`--share=/dev/video0` gives access to the webcam.
What is the step to allow the microphone and speakers?

I'm not particularly familiar with how audio devices are working. I read they 
are in /dev/snd, but sharing this or even the whole of /dev/ doesn't make the 
microphone and speakers available (although the browser is now asking me for 
the permission to access them, so it seems aware I have them). I also tried 
adding tinyalsa and pulseaudio to the container in case that's what's missing, 
but to no avail. I didn't explicitely install anything related to audio (but I 
have %desktop-services in my operating-system definition), so if it's a 
software that is missing, I don't know which one.

Thank you in advance!