I want the LLM outside of the apps, telling the apps what to do on my behalf and gathering information from them privately towards doing what I ask it or answering questions I have for it.

If an app is a gateway to a bunch of data, it's cool to be able to "talk" to that data via any built-in LLM-based stuff, but typically the app is just a frontend anyway in that case, so the app isn't really needed.