Unfortunately this runs into their "have to move off AWS for managed service" point since the managed service for Citus is now on Azure post acquisition, as Azu

Unfortunately this runs into their "have to move off AWS for managed service" point since the managed service for Citus is now on Azure post acquisition, as Azure Cosmos DB for PostgreSQL Pitching Citus ran into issues where people were hoping it would handle sharding transparently, which isn't the case. But for someone who's evaluating rolling their own sharding, being able to manage sharding keys explicitly is how Citus allows efficient joins based on your workload. So yes, if you're looking to roll an unmanaged sharded postgresql cluster, consider starting with Citus