postgres 11.3 checksum validation post migration

I am in the process of migrating our AWS RDS postgresql from one account to another with zero downtime. I am going with pg_dump/pg_restore + AWS CDC for ongoing replication. I am looking for a way to generate and compare checksum to make sure no differences in data or corruption. Q1: Is it possible to generate checksum on the database level rather than table level? Q2: OR doing a select count(*) on all the tables in source/target is better? when there is no downtime, data changes will be coming in the source during this process and i am afraid this will affect the checksum or rowcount comparison. Please advise