I recently shipped some cordless tools. i told fed ex about the batteries and they said “uh huh.” then they shipped them
I know with usps, it doesnt matter what level you ship them at, 1st class or priority, they all get sent ground. Fedex may have different standards in terms of how big a lithium batter has to be bedore it goes ground only, and sometimes it makes a difference if the battery is by itself/tool battery, versus it already being inside an electronic item, like a fitbit. The size of the battery changes how they ship and whether or not its a standalone battery versus being inside something, makes a difference.