Do you want to access other users' data? I'm guessing you want to call the data via an API to semi build a new interface or something? No it's not available on our vanilla product. Again, Muut IO is the way to go for more complex stuff like that
I didn't see anything about private messaging in Muut IO. Is there some documentation for that?
You'd need to build your own private client. Since Muut IO is super modular you can build whatever type of system you like. All the conversation enpoints [start here in the docs](https://github.com/muut/io-client/blob/master/API.md#conversationpost). Everything starting with "conversation" is a private messaging thing.