Debian has a package called
indicator-power which notebooks use to show the current power.
I have a working voltage divider and ADC wired up to my external power source, and I have correct reading from the GPIO.
Can I somehow feed the readings into the input of
xbattbar and have it work just like how notebooks do?
I don't know if there are alternative packages, but anything that has a dynamic icon, be it numbers or a bar, on the top panel will suffice.