With Zigbee it is already possible with a few hacks but I got used in Homeseer to use multple rings of Zwave (With their Z-net devices) and would love to see this option with Zwave. Shouldn’t be a big issue with the MQTT side so it just needs multiple input options.
The ZWave integration already supports more than one controller, you just add more instances and point them to the zwave_js or zwave_js_ui instance running elsewhere. Are you talking about multiple instances of the zwave_js or zwave_js_ui addon?
If you want to run multiple controllers on their own separate network this is easy to do. You just Connect each controller to their own instance of Z-Wave JS UI. Then in home assistant you add multiple Z-Wave Js Integrations and connect them to each instance of Z-Wave JS UI. Once setup you can control both networks from home assistant.
If you want to run multiple controllers in the same Z-Wave network then you will need additional software as this functionality is not available natively in HA.
Multiple controlers in same network would be optimal but I can live with grouping several controllers in separate networks. Didn’t get it to work when I tried but if it is possible I need to try harder
Thanks for the feedback here.