Is this a use case for user custom fields?

I’ve seen those. One difference here is that I am happy to build out an entirely separate app that then interacts with the discourse API to give the user the experience of creating a subgroup. So I can create the subgroup myself in the separate app, associate members with it, etc.

But I would like to still be able to use the discourse front end posting functionality (creating topics, replying, linking to categories, and adding tags mainly) on that subforum page that my app has created.

I was told that there is a way to link user custom fields with tags, or something like that, to limit the tags a user can post to.

But the underlying hope is what I’ve mentioned–I can take care of a lot of the subforum setup on my app’s end, but it would save me a lot of time to still be able to use discourse’s posting functionality.