Some time ago I had created a node that offered some configuration, but my node didn't really worked with input/output messages. The feedback I got from the community was that I had to create a (right) sidebar panel in the flow editor, instead of putting my configuration on the config screen of a normal node. And they were right, so I created a (right) sidebar panel in the flow editor. Because I realized at that moment that I had developed a node, only to have a config screen where users could enter the configuration data. But indeed it wasn't really a full blown node, that handled messages...
Could that perhaps be a better solution for your use case, if you don't have an input or output? Regardless of the extra work involved of course...
