FitoTrack has the option to regularly export data. 

One would need setup one's own cloud sync that would look into the directory and sync it. The other device would also need such a setup.

An auto-import functionality does not exist, though the data would be synced, so one just needs to manually import the data.

There is also another way...

The export mechanism allows defining an URL. FitoTrack will send POST requests to this URL frequently. You can read more about it here: https://codeberg.org/jannis/FitoTrack/wiki/Auto-Export