A very simple thing that HA OEM’s could do right now to help guide users of rechargeable batteries is the same thing Apple does for its devices.
Just have a “Battery Health” monitoring function in the firmware/smartphone software. Not an Apple user long enough to know how reliable it is, but I open that applet for my 2.5 month-old Apple Watch, it says “100% Maximum Capacity” and “99% Maximum Capacity” for my iPhone 6S, which had its battery replaced a month or two before the wife stopped using it and later gave it to me. Her 2-year-old XS MAX reports something like 92% Maximum Capacity.
The point of this is that it simply gives you a real guestimate of where you’re heading with your usage habits for your Li-ion battery. You don’t have to wait until you’ve killed the battery to find out approximately how long the lifespan of your device is going to be if you keep operating the way you are.
Apple’s great web information has told me that I can expect my Apple Watch battery to last the equivalent of 1,000 full charge cycles before it drops to 80% of maximum capacity. My particular usage is such that I can go ~2 days on a full charge (I operate ~100% of time in Airplane Mode still using fitness and sleep monitoring all the time and HA control only as needed). And 2.5 months along, I haven’t dropped a % from full capacity. I would estimate the watch battery will last ~5.5 years (1,000 charges/183 charges/year, for me). My watch only charges wirelessly.
Unless Apple has somehow cornered the patents on such battery health monitoring and reporting, there is no reason HA OEM’s could not provide the same information to their users. The HA OEM’s may say a rechargeable HA will last 5 or 6 years but they give no idea of number of anticipated usable full charge cycles, no battery health reporting, no ability to set alerts when charging or discharging your HA battery (I guess it’s difficult enough, based on Google Play and App Store reviews, just to write a basic smartphone app that users have any respect for). HA OEM’s need to up their game when it comes to just even plain old low-tech rechargeable battery monitoring and better battery longevity parameters. Apple can do it but why not HA OEM’s?