For anyone searching for a solution to get peppymeter installed on volumio with the subject outputs, google keeps pointing to @2aCD’s awesome solution here. Unfortunately this plugin doesn’t allow serial or PWM outputs, but the subject does mention @balbuze’s plugin, which does. Sadly, the link to balbuze’s github was a dead end, but with some digging around I found it and successfully have peppymeter installed outputting to serial (RS-232), with some minor tweaks.
Github location:
https://github.com/balbuze/volumio-plugins/tree/alsa_modular/plugins/user_interface/peppyMeter
The instructions are mostly correct, but the wget command should read:
wget https://github.com/balbuze/volumio-plugins/raw/alsa_modular/plugins/user_interface/peppyMeter/pipe.zip
and the plugin is missing the python3-serial dependency, so you will need to install that using your preferred method. For example:
sudo apt-get install python3-serial
Tested and working with serial output on Volumio 3.378.