Hi @Jenkler! Long time no see 😁
I don't think we can do this right now, since visibility is handled on the category level.
It could likely be done in a plugin though, to enforce visibility on a per topic level ..
Is there anyway to add new fields to topics or posts for custom sorting?
There is no way to do this in core. Are you trying to make a plugin to do this?
For adding fields to a post/topic you would use the hooks as so:
Sorting is another matter, you need to also add the fields to a sortedSet in the db, here are two examples:
You mean add tags after the fact? Only a mod or the OP can edit a topic and add them.
Tags are not available for posts but I really, really, wish they were.