But frankly, if 10k/s inserts is the scale you are talking about even worrying about a pub/sub solution seems odd.
Introducing something like Kafka for anything less than an order of magnitude more than that seems like an architectural blunder. By the time you are there Postgres will have obviously disqualified itself.
And Kafka isn't the only solution for it. There are many lightweight pub/sub and queuing systems which also don't involve needlessly adding abstraction layers and application code into an RDBMS.