Hide post from public feed, index and search. but show in a private custom feed

Is this even possible?

Basically I want to create a special feed just for a third party app that’s private.

Ideally, I would like to have a special “hidden” category that doesn’t appear in the main rss feed or main index page but would allow me to call the specific category name in teh feed to get the hidden data for my third party app.

Is there a plugin that allows that? I saw one called ZipLine but couldnt find it listed in the plugin db for wordpress so i didnt want to chance it.

So i want a custom hidden feed generated off of a hidden category.