I have started working on an implementation of Restrict exposure of full name to certain groups, and just came across this topic, which completely intersects with what I am trying to do.
My approach is to replace SiteSetting#enable_names with a new Guardian#can_see_full_names?, in the appropriate contexts. This new guardian predicate checks the user context against a new site setting, full_names_visible_to_groups.
I don’t want to inadvertantly step on any toes (or duplicate any work) — are there any updates to the status/planning for (1)/(2)/(3)/etc above, and is there any unpublished (i.e., not in main repo) work/code that I should be aware of?