> I want to rewrite some of my setup, we're doing IoT, and I was planning on

Is this some scripting to automate your home, or are you trying to build some multi-tenant thing that you can sell?

If it's just scripting to automate your home, then you could probably get away with a single server and on-disk/in-memory queuing, maybe even sqlite, etc. Or you could use it as an opportunity to learn those technologies, but you don't really need them in your pipeline.

It's amazing how much performance you can get as long as the problem can fit onto a single node's RAM/SSD.