RDS Replica to different database

I would recommend that you explore AWS DMS

AWS Database Migration Service (AWS DMS) is a cloud service that makes it possible to migrate relational databases, data warehouses, NoSQL databases, and other types of data stores. You can use AWS DMS to migrate your data into the AWS Cloud or between combinations of cloud and on-premises setups

You can perform one-time migrations or replicate ongoing changes to keep sources and targets in sync.

You could run this on a daily basis to keep a 2nd type of database in sync

This may give you what you are looking for https://docs.aws.amazon.com/dms/latest/userguide/Welcome.html