Logical Replication/Foreign Data Wrapper Connectivity between Two Aurora Serverless Databases (PostgreSQL 10.7)

I have two Aurora PostgreSQL Serverless databases running in the same region and have PostgreSQL version 10.7. I’m wondering if logical replication is available? The official docs say that it’s possible for Aurora PostgreSQL, but nothing specifically about Serverless databases.

It times out when I tried to run this command with the right credentials:

CREATE SUBSCRIPTION testsub CONNECTION 
   'host=publisher-cluster-writer-endpoint port=5432 dbname=db-name user=user password=password' 
   PUBLICATION testpub; 

I also struggle to have connectivity set up for Foreign Data Wrapper between two Serverless PostgreSQL databases.