Have you looked at syncthing? I believe it ticks off all your boxes. I'm using it to sync my obsidian vault and Todo list between multiple android, Windows, and Linux devices and it Just Works. I do have an always on server running it as well to both maintain a backup and to catch any notes devices powered down might miss, but it's not a requirement.

Personally, I use Syncthing to sync all my notes between computers and my phone, it works great!

I do plan on adding vault encryption and cross device sync (literally making a list of updates atm). Like tacostakohashi mentioned, I too have been thinking of using git for cross device sync.

> it's still an unsolved problem to sync files with end-to-end encryption between devices, without also having to use some specialized application.

How about using git, over https or ssh? Or are those 'specialized'?

Git is not that convenient to use on the phone.

I don't plan on making jot mobile compatible. Maybe in the future, but not right now.

Is vim?

I do this with termux + keybase git.