I would imagine most devices have BMS settings to deal with this now.
There's not much incentive to do that. Battery longevity reduces sales. Keeping the battery at 100% gives better review scores. It's a lose lose for phone makers to implement that.
Where are you going to buy your replacement gasoline engine and transmission? The previous owner decided that oil change intervals were more of a guideline anyway. One big win in buying a used EV is that maintenance is minimal, so there's less worry about how the previous owner treated the car.
I promise replacing your drivetrain at 200k is going to cost more than a battery pack.
I can get an aftermarket LiFePo battery replacement for my prius for 1/10th the cost of an OEM. It's just a bunch of laptop batteries in a box, it really doesn't have to be super expensive. As adoption grows aftermarket battery replacements will plummet in price.