I’d like to suggest a new restriction toggle in the outliner that disables and enables the following behavior.
This toggle would make the movement of one object affect the position of all others in the collection. Like when one parents all objects to an empty to be able to move the objects together, except all objects function like that empty.
It shouldn’t work just with motion, other transformations too.
Maybe it could be implemented simply: select all when selecting one.
This makes it seem that it could be a selection tool/option instead of an outliner toggle, but with a toggle is easier to do what you want in collections inside collections.
Collection instances can be used, but what about the original collection? How do you transform that?
Plus, how do you manage sub-collections?
With instances, It would be better if you could enter an instance collection with a tab and start editing, but there would still be the issue of managing the original collection, and include or exempt sub-collections as necessary. That’s why I thought a toggle would be a good idea, but maybe a tool would do…
It would be great if the need would be addressed in whichever way the developers seem fit.