There’s an existing feature suggestion discussing an option to group extras of the same type inside the extras hub (which is pretty much what you’re asking for except it’ll keep the extras separate from the main media).
Unless you insist on throwing the extras in with the main content of your show (for show-level extras; I suppose it’ll be similar when listing season-level extras alongside episodes?), I suggest you comment/vote in that existing thread to avoid redundant suggestions.
