i'm trying to nudge Grafana into the direction of IoT/SCADA control, so we can be both, a great way to viz (data sources) and to control (data sinks). not personally a huge fan of having to recommend Home Assistant for that use case :)
similar to how you can make plugins for data sources, you can make plugins for data sinks, like write over modbus, or POST to http API or, publish to some kind of MQTT broker, etc.
since IoT devices have limited storage, usually the metrics are dumped into another system like Prometheus. but that Prometheus data source used plotting cannot be used to control the device, which will have another endpoint and another API, so we need some kind of concept of data sinks. at least that's my idea right now, allow data links configured in the panels to poke some "data sink" with values that are available in the DataFrame or custom-entered into the UI, like we do with traceID for Exemplars, etc.
Have you seen/know about NodeRED? I myself have moved away from HA/OpenHAB-likes to NodeRED as that allows me control that's more... restricting. At its heart NodeRED is a visual programming tool (and I think it wouldn't be a terrible fit for Grafana), but what NodeRED has and Grafana doesn't is a community which built a very significant number of packages that integrate with various protocols and devices used in home automation.
I see a potential for some integration and/or idea sharing here. But it is also important to understand that the set of people who want to fiddle with their homes is much, much larger than the set of people who (are able to) program. Which is why HA and the likes are so popular.
(i work at Grafana Labs)