LOL, docker for running mosquitto at home? Who does that?
It was convenient. The official docker image includes all the tools you need.
Overkill? Sure. It sips memory and compute, but when most everything else is in docker, what is wrong with one more container.
I did a write-up here:
https://github.com/NortySpock/selfhosted-show-wiki/blob/bca6...
(Eventually I did switch over to NATS emulating an MQTT endpoint so I could get a broker with Prometheus-scrapeable `/metrics` endpoint )
Just to re-iterate, Unraid is a proprietary Linux OS based on Slackware Linux. It is generally ill-advised to ever run tooling directly on Unraid when a Dockerized equivalent is available.