Well usually you use a datastore on a server as a master, then you pull/push based on timestamps. Firebase and cognito/appsync work this way, basically. You c

Well usually you use a datastore on a server as a master, then you pull/push based on timestamps. Firebase and cognito/appsync work this way, basically. You can use any data store you want on the server to do that. You could theoretically push a local sqlite db up to s3 as a sync mechanism, I suppose, if you do the locking correctly.