A link about maximizing battery health was posted in the old Graphene IRC room in May 2021.
Two relevant excerpts from the link:
If you want to keep your phone's battery health in the best possible condition it possibly could be in, you must use the Google charger and cable and keep them all plugged in around the clock.
...when your phone's battery is reported at 100% and charging, the battery enters idle maintenance, which ensures that the battery is not going to self-discharge, without overcharging it. In this state, the phone can remain online and be powered by off external power from USB, rather than using the battery. This is important to the health of your battery by reducing the amount of demand you're placing on it.
Other posts on this forum say similar things:
[deleted] We have no interest in implementing outdated battery things like adaptive/slow charging. The phone's battery controller handles this already, just not GUI-facing.
My battery usage is to keep my Pixel plugged in with the original Google charger and cable for the majority of the day, unplugging it for a continuous 6-8 hours per day. During this time, my battery drops from 100% down to around 75%, at which point I plug it back in and charge to 100%. Is this usage pattern more harmful than a more typical usage pattern of, for example, using for as many hours as needed to get to 50% then fully charge back to 100%? Is it true that going twice from 100% to 80% is worse for battery longevity than going once from 100% to 60%? This question comes from the idea I have heard that spending time in the [80, 100) range is the worst range for a battery to spend its time in.
Secondly, I am considering purchasing an ethernet adapter from a reputable manufacturer that offers pass-through charging. I will likely follow one of the recommendations at https://discuss.grapheneos.org/d/96-usb-c-to-ethernet-adapter-compatibility-list . Without a GUI-facing indicator is there any way to confirm that the adapter is allowing the Pixel to go into idle maintenance mode? Or can such an indicator be made to be GUI-facing? There are no indicators visible after dialing