

MQTT is just a messaging protocol, it’s mostly used for iot purposes like you mention, but can in theory be used for any kind of project.
Never used ejabberd, but one of their selling points are multiprotocol support, so it’s not so weird to support a multipurpose standardized messaging protocol.
Looks like great fun! Will definitely give this a whirl soon. Seems to be a bit of a departure for Pathia though, could be interesting