Is this a use case for user custom fields?

[Falco]

@JQ331

The key piece i am missing is the ability to limit users who can post with that tag.

That key piece is not something on the roadmap, and not something we plan to add.

There were many topics on this over the years:

User-Created Categories

This is really far off. If you trust your users that much, make them all admins as a short term workaround. Otherwise create a topic for new categories and have people post to it when they need a new category… watch that topic as admin, and voilà

How to allow users with L2 to create subcategory

The way discourse is designed, category creation is something you do very rarely. It doesn’t make sense to let non-staff do that. However, tags can be created by non-staff users. Maybe that could be something for your use case?

[HIRING] User creating categories plugin

What would you like done? I need someone to make a plugin where any user (regardless of trust level and regular/mod/admin role) can create categories. Then to completely rename Categories to any name I want (it’s always editable). When do you need it done? 1-2 weeks What is your budget, in $ USD that you can offer for this task? $200, more if done superbly.