There’s a caveat that you have to start on an older version of Nodebb, but:
Edit: looks like it was updated to support a more recent version of NBB 🎉
Go to categories and open category settings. You should see a list like below:
In this case I am only allowing members of the certain group (Enigma) to see or post to that category, but you can see you have lots of option to control access to each category.
Some eclectic groups going on there, @arasbm.
@arasbm Thank you very much. That''s what I was looking for. As you can imagine, I just didn't dig quite deep enough
Aww I actually had a canned response for that, anyhow ye thats pretty much the only way to do it