I do not.
I’m not an engineer, so I’m not the best person to ask this. In my mind how many obstacles you hit are related to how “full-featured” you make this plugin.
For example, will these posts tags be searchable? That’s another system you need to integrate into.
Will they be visible on the /tags page? Another system.
How will users be able to see all posts with a tag? Currently the tag view is a topic list, not a post list (https://meta.discourse.org/tags/faq-material).
etc.