I realize this is an oddball request but is it possible, perhaps via a data explorer query, to retrieve a full list of posts in a specific category that has been read by a specific user? Is it possible to create a list of topics and posts a user has seen generally? This might be interesting.
My story is that we have a private category which admins are not supposed to be reading. Everyone knows and can live with the fact that we have to have access to it for admin purposes but the understanding is that we mute the category in our prefs and do not actively go seek out messages in that category. Knowing that there’s a paper trail will help us to resist the temptation to do that.