The Chargie is also useful if you want to set an arbitrary charge limit. iirc on Samsung you're stuck with 85%, can't change it.

Another key thing for the Chargie is that it will cut power after reaching its requested charge, and only resume charging again if power falls to a certain level. This prevents the "trickle charge to maintain the precise percentage" thing that is a real killer for batteries.

Yep, called "Protect battery" or similar. Lots of phones have it, even quite old ones.