Cumulus Support

Would be nice if there was some way to run cumulusmx on an Homeassistant (hass) machine, either as, an add on or as an integration. You can send the data there via mqtt, or which much thanks, but afaik Cumulus mx won't run on the actual home assistant system?

Unlikely to happen. You could run HAOS in a docker container or install HA on a Linux box as software. But making MX run under HAOS is not likely to happen.

I'm running Home Assistant Core on a Raspberry Pi 4, there has been moments when the Add-On Store could have been useful but otherwise
Installing and running CMX4 should be very possible