Volume widget is a program, which shows system volume levels. It needs pulseaudio, alsa-utils, python3 and python-pyqt5 as dependencies. Note that dependencies might be different depending on your distribution.
#Volume widget Copyright (c) 2017 JJ Posti <techtimejourney.net>
#Volume widget comes with ABSOLUTELY NO WARRANTY;
#for details see: http://www.gnu.org/copyleft/gpl.html.
#This is free software, and you are welcome to redistribute it under
#GPL Version 2, June 1991″
Here are some screenshots