Postgres Logical Replication For Specific tables
Have you tried specifing the list of tables to be logically replicated while creating the publisher?

Create publisher pub_1 for table table_a;
Create subscription sub_1 publication pub_1;


This will send the changes only for table_a to the subscriber.
This is the way to whitelist a selected set of tables to replicate.

ALTER PUBLICATION name ADD TABLE table_b;


This Alter publication command can be used to add/remove any tables after creating a publication.

I dont think there is a way to do this with replication slots.