Could you look into adding a battery report for all devices? Perhaps just add it to the device descriptions in the Device List?
I created a dashboard for all the devices I have that return battery levels, but I've only got 14 of 'em (at the moment). A better display option would certainly be nice.
Also, you can use the built-in Notifications app to create a notifier when the "Battery Level" of any (or all) of your connected devices fall below a level of your choice.
I use HomeKit via Homebridge purely for the Dashboard. The UI is much better and it reports battery levels for all devices and shows warnings on the main page for any devices that are running low. Just an option.
I have a dashboard setup with all of my devices so I can see the battery life too but it is kind of a pain looking through them and keeping the dashboard updated.
Every time I look at the device list I wish there was a way to customize the columns. I would get rid of Source and add in Battery and then sort by that!