What sharing and collaboration features would you find useful?

I'm still trying to get a sense of what sharing and collaboration features would be useful in Joplin. By this mean any way to share a note with someone else or have multiple users collaborate on the same set of notes or notebooks.

If a feature like this might interest you, I'd be helpful if you could describe: how would you use it? How would you expect it to work?

All this might not be implemented right away, but it will inform how the development should happen for example by making sure that even if a feature can't be done now the software is done in such a way that it's possible to add it later on.

Any idea or suggestion is welcome!