Syncing local database to production database

Hi, I want your suggestion for two setups:

Note: Whenever I used Data it means 100s of GBs of Data so please suggest me something accordingly.

  1. Is it possible to add all data in a local database and then sync everything to an online production database. Considering that the data amount is huge. How can I do syncing of local and remote? Would Replica set work in this case (i.e have one local (primary) and maybe one online ( secondary )

  2. Is it possible that all docker containers running their own database and then I merge them to one local database and push the data to online database? I was thinking of multiple docker db and then merging (to avoid concurrency issues instead of using transactions )
    Docker containers let’s say are 10 and have 10 individual databases but then somehow I merge them to one local and push it to remote.