Well i did say it was the simplest solution. I think you made a good job of verifying that it's also the most real, though: installing -devel packages is asking for trouble if you're not comfortable with the unix filesystem and command line apt tools. As that is common knowledge, it's acceptable to tell users worried about their rootfs to uninstall said apps and leave it at that.

He's talking about windows and file explorer to peep his disk usage...

and you're suggesting a shell script.

Hopefully one of the two suggestions will get the job done, but it's a disservice to ordinary users to claim that the "real" usage of the device will require shell scripts and "some luck".