My OnePlus 7t also has this feature, but it was added as a recent Android software update. It’s great to see that it’s on the Pixel! This probably means that it’ll probably be distributed among other flavors!
If the battery greatly damages itself by charging past 80%, then the device should be aware of that and accommodate. I should never have to set an alarm to unplug my phone in fear of destroying it. This isn’t the 90s, where we tried to avoid over-charging Ni-Cd batteries. Making it work for the lowest common denominator is the only way to do it.
If, you know, you’re a company that doesn’t want your customers to buy more of your stuff. Yay e-waste.