FEAT "use local storage” + Syncthing

[fccfc5d245c]

Is your feature request related to a problem? Please describe.
At the moment, we can only sync through the unencrypted cloud. Some people don't even like encrypted clouds. Others won't know how to self-host when that's available.

Describe the solution you'd like
Could we onboard several devices with "use local storage” and then use Syncthing to keep our tasks synced? Seems like an easy solution for the privacy concerned but not too tech-savvy user.

Additional context
I use Syncthing to keep most of my files synced between an Android phone and a Linux PC, then edit them on each platform with whatever software I need. It's a good way to keep my files to myself and, above all, it works.
I wonder if it's possible to do it already but, if not, I suggest we should be able to do it. We only need access to the files that need to be synced on each device.