So, I tried to use the Chargies to limit the charge in my Fairphone 4. But sometimes what you need is right there, staring you in the face…
I was browsing around in the settings to see if any of the options was preventing the Chargies from working properly, when I found this:
Like… really?
And it actually works:
I don’t know if this is available in the stock Fairphone 4. Mine is running CalyxOS with the July update.
Did I mention that I am mighty pleased with my deGoogled Fairphone 4? Here’s another reason 
No Chargies needed at all!