Best way to setup DB sync for offline Android meteor app?

Is there a known best approach to getting data from a Meteor mobile app to sync with a server?

The app would be the primary UI the user interacts with to plug in data, but I want it to be offline first on the app first, so right now I’m considering using GroundDB for that, and then have it sync a copy to a server second.

Does this sync have to be something I build manually or are there already known solutions for this? Oh, it’s gotta be free off the bat too, I might not make any money on this app, so don’t want to put any money down right away.