I’m not aware of any current plans to tag the Step Deck by any clinical textbooks (other than the existing FA tags), unfortunately.
Tagging takes a significant amount of work, and time, and so the limited resources available for that work tend to prioritize resources that will have the most uniform reach and that are highly specific to the Step exams, specifically. (FA, BnB, etc.). Individual clinical textbooks naturally vary in their scope, quality, and overlap with the Step exams.
Nothing is impossible, of course, and you can always add your own tags or details in your local collection as many folks do for any number of things (lecture notes, missed questions, etc.).
Please let me know if that answers your question, and if there’s anything else I can help with. 