I’d like to please hide some icons from the list of applications that appear in Gnome when clicking on the Show Application 4-dots icon in the dock. This is for preventing my parents to click on admin/system application that may eventually mess their computer. I could avoid making their user account of the admin type but I have anyway to provide them the password eventually so I prefer this “hiding tweak”. I’ve also read somewhere else then the hiding of the icons may eventually be overwritten when applications get updated. If possible I’d like to avoid that. Many thanks! 
I have a feeling this will not be easy. I am sure it can be done but not permanently without it being broken by point releases and app updates. This would be trying to achieve what most GNOME applications can’t. I would also put the question out in some other forums (Arch etc) where you have some users tinkering with this kind of stuff.
The desktop launchers are under /usr/share/applications/ so I guess that removing or otherwise editing some of those files should make some applications “invisible” to Gnome, while still allowing to start those applications via the command line.
A change like that is going to be reverted by an application update though…