@the-mentor I am not sure what you mean by “this” and “battery management”. Are you talking about more than notifications?
A user is able to define an automation to produce notifications quite easily. However, it would be nice if Home Assistant shipped a notification automation out of the box (with the option to be edited or removed by the user upon free choice)
A probably more important argument to add is Interopability and Guidance.
The various integrations implement slightly different battery indicating entities. This is due to the nature of devices and proprietary limitations, but also influenced by developers preference. The provided solutions in previous posts solve the WTH request only for a couple of those options we see in the wild.
The Home Assistant core and developer documentation should provide clear guidelines which battery entity styles are encouraged and how integrations should implement them. This would solve a lot of things and make the necessary automation a lot easier.
Lastly, this might be out of scope but relevant in this context: I would wish ambitions in the direction to equally address unavailable devices, which is just as critical.
Some of my devices already have the type and number of batteries listed as attributes on the battery percentage sensor. From a quick glance around my instance it seems to be just ZHA devices reporting this information. I agree it would be great if this was available for all devices.
On the same topic - here’s one for device manufacturers. Why can’t we have 2 coin cell slots - a primary and a secondary? Tell us when the primary has died and automatically switch over to use the secondary.
Then we just need to swap them over and put in a new secondary within ~1yr. No more outages.