In my mind at least this would be solved by the "vault" needing to be decrypted with a password every time notes are accessed/saved with the password acting as the key? I'm not terribly well educated on encryption though.
After some more research it seems that Joplin only E2E encrypts notes at transport and not at rest[1]? e.g. it only stores plain text files on the harddrive just like Obsidian does? This sadly makes it not viable for my use case :/
In my mind at least this would be solved by the "vault" needing to be decrypted with a password every time notes are accessed/saved with the password acting as the key? I'm not terribly well educated on encryption though.