In a nation unwilling to require background checks or a fundamental demonstration of competency to purchase a military style semi-automatic assault rifle with a high-capacity magazine, it's difficult to see this happening.
You can purchase 3rd party chargers that have a setting to charge the batteries to 60%. I have these for all my drones. They have the added benefit of being able to charge 4 batteries simultaneously. I even have one for my Air 2s that will...
Yes, it's fine to do that for battery maintenance when they aren't currently being used.
Some people like to keep their batteries ready to fly at any time, so they get into the habit of fully charging the same ones every couple of days without...