Move RDS postgresql database to Aurora Serverless

If you're not on RDS for PostgreSQL 10.7, you'll need to upgrade to that version, then you can create an Aurora PostgreSQL read replica for your RDS for PostgreSQL instance.

After promoting the read replica to be a standalone read/write cluster, you can then take a snapshot of your newly created Aurora PostgreSQL (provisioned) cluster, and import that snapshot into an Aurora PostgreSQL Serverless cluster.