Sorry to jump in a few months later..There's a package for it - Mosquitto 1.6.15 - which you'll need to install.
After that you're kind of on your own to concoct the necessary infrastructure.
If you're interested and capable, I can upload it to the repository for you.
I know nothing about HA I'm afraid.
Would you be able to release the source of it please? On the package page.. I don’t see the source listed, only the package or bundle file.
I would like to try compile it for the foxsat hdr (or make an attempt)
I’m a HA user as well and stumbled on this. If successful… Might be able to document it for other users.