This is the standard I've encountered at coffee shops and school libraries, no one seems to mind. However, it would be easy to build an app that alarms when the battery becomes disconnected (i.e. someone walks away with your stuff).
Wait what? How does this work?
On OSX:
pmset -g rawlog
Output:
$ pmset -g rawlog pmset is in RAW logging mode now. Hit ctrl-c to exit. * Battery matched at registry = XXXX 01/15/20 XX:XX:XX No AC; Not Charging; 75%; Cap=5490: FCC=XXXX; Design=XXXX; Time=X:XX; -752mA; Cycles=14/1000; Location=XX; Polled boot=01/15/20 XX:XX:XX; Full=01/15/20 XX:XX:XX; User visible=01/15/20 XX:XX:XX
I expect there are more elegant solutions, but this would theoretically work, as I used to use this among other things to track my daily laptop usage to see how on task I was any given day. If the lid is closed but unplugged then I was probably going to/in a meeting, if the lid is closed and charging then I was likely afk, not working. Worked pretty well to give me a ballpark of my productivity.