Hi,
It is currently possible (though not supported through the UI) to give a user access to only specific entities. However, they still have full access to the logbook and there doesn’t even seem to be a way to let only certain users access the logbook.
I think that it could potentially be quite complex to only show a user logbook events that pertain to entities that the user has access to, so I would propose that a feature is added that simply allows you to specify which users can see the logbook and which ones cannot.