Is there a way to show me row counts of the various objects in CRM, before I choose them for replication? I don't want to select empty objects, for example.
You can check row counts via Skyvia Query Tool. For this you need to select your connection, then required object and perform the query like this one:
FROM account AS t
Please note, Query Free plan allows executing only 5 queries per day: https://skyvia.com/pricing/#query