I would like to suggest having the E2EE work not for all notes but per notebook even if notebooks will not be shared.
This will allow you to have your private/personal notebooks and your shared notebooks which can be accessed to other users on Joplin Cloud/Server
- When you create a new notebook, you will choose which encryption key to use saved in Joplin or use a new encryption key.
- You can also change the encryption key to a notebook anytime by re-encrypting the notes
- You will have your encryption keys be labelled in Joplin to easily manage multiple keys