abiltiy access data folder in unrooted android phone

I have seen this done in Autosync, would it be possible to implement the ability to sync files within the data folder on android? Thanks

I highly doubt any app can access the /data partition without root unless the OS itself is a custom ROM that is less restricted and/or you perhaps need enable some additional permissions with ADB for the specific app. When it comes to Syncthing though, root is probably your only option at the moment.