Each of us has a bunch of gadgets for any type of work. For example, I have a tablet, a couple of smartphones and computers. But keeping track of the battery charge on such a heap of devices is not so easy. But there is a solution for this too.
Batteries will help you keep track of the battery level of all your apple devices from any apple device.
The utility does not require any configuration, it is enough to install it on all your devices and you will see the charge level of all other devices.
This is how it looks on iOS.
And this is how it is on macOS, where you can additionally specify at what level of charge to receive alerts.