iCloud Drive greyed-out folders and files

I have just had a lengthy but very helpful phone call with Apple Support (Ireland), the conclusion of which is that I am seeing greyed-out folders and files because these are hidden files and somehow I had invoked "show hidden files". This Finder feature is toggled by the key combo Shift-Cmd-[.] (dot, period).

These hidden folders and files are meant to be there, even if they relate to apps or material I no longer use on any of my devices. Deleting them (which we found is possible in safe mode) may apparently adversely affect device functioning in unpredictable ways. So best to keep them hidden, or learn to live with them. Occasionally, it is helpful to see certain hidden folders (e.g. ~/.ssh and ~/Library) and their contents. Unfortunately the Shift-Cmd-[.] toggle cannot be applied to folders selectively: it is all or none.