Here's my side project StarQueue which is a free message queue.
I built it because I wanted to see if it was possible to implement something similar to SQS using Postgres as a back end. I actually implemented the back end in Postgres, MySQL and also SQL server and they all work fine. I chose Postgres in the end because of personal preference. I tried to implement the same back end in Oracle and the experience or using Oracle was horrifying so I dropped that. I tried to implement for IBM DB2 but that got hard for reasons I can't recall so I dropped that too.
It's written in async Python using the Starlette framework.
It's in beta at the moment. Let me know if you notice any problems.