Fetch Pin config by MQTT?

I've got a few Unos and Megas dotted around the house driving 1-wire temperature sensors, and 8 relay boards controlling heating, lighting and appliances. These are driven from Homeseer.

The Arduino plugin for Homeseer lets you configure each pin from within Homeseer, which means I don't have to go and update the sketch in the awkwardly located Arduinos every time I change something, and maintain copies of each sketch.

I'm moving across to Home Assistant, and starting to experiment with integrating everything with MQTT.

Has anyone created a sketch that will pull the pin configuration from an MQTT topic which could be stored and maintained in Home Assistant? Perhaps based on Arduino MAC address?

The standard way to integrate Arduino with HA is to install Firmata but you could try MySensors as I think it supports MQTT.

Thank you. My arduinos are already ethernet connected, so Firmata wouldn't be suitable. MySensors looks like it might work though. Thanks.