This daemon is used to control system microphone via AirPods button.
You need to double click button to toggle mute.
This will work in HFP/HSP profile. For example if you are in a Zoom/slack/WhatApp call, so you can click button on your AirPods to mute yourself.
This is POC, but it works very well ;)

mkdir -p ~/bin
cp airpods-mute.sh ~/bin
mkdir -p ~/.config/systemd/user
cp airpods-mute.service ~/.config/systemd/user
systemctl enable airpods-mute
systemctl start airpods-mute
mkdir -p ~/Documents/airpods-mute
cp sounds/* ~/Documents/airpods-mute/

Add this envs to wireplumber user service:

Environment=PIPEWIRE_DEBUG=spa.bluez5.native:4
Environment=WIREPLUMBER_NO_PW_LOG=1

You need to install amixer, mpg123, journalctl