[Feature request] sync & merge among devices

[photonism]

Checklist

• I have searched for existing issues (open and closed) and confirmed this feature hasn't been requested before
• I believe this feature request will benefit more than 10% of users, not just myself

Feature Description

the ability to sync & merge among devices, instead of just import and override, is highly appreciated.

• users can sync with git, syncthing or anything else, so no sync server is needed.
• paid sync server access is also appreciated.

this will enable users to use PipePipe-X among devices, etc. phones, tablets, TVs, linux computers (with waydroid), without having to use the app primarily on one device, overriding everything on sync.