It's literally a watchdog for your battery levels. Research shows that batteries that are kept charged between 35%~80% are more likely to last longer.
Everything else other than the statement mentioned above.
Just download the binary file on the releases page(zipped), and let it do its thing. Don't forget to enable notifications for it, and don't keep your machine on Do Not Disturb mode, it won't work as intended.
Of course. This was made only because I keep forgetting to plug and unplug my charger at the optimal time. Feel free to use it however you want. Just don't sell it, I guess?
Like I said, this was made for my use, I wasn't considering other platforms. Feel free to create a pull request if you want to add other platforms.