Custom RRD Commands / Custom Graph Plugin

I know variations of this have been requested, but usually much larger in scope than what I have in mind:

Current graphs have the ability to show you the RRD command that generated them. Using those as a reference, and a little bit of googling, you can put together your own commands. It would be really nice if there was a way to put my own custom RRD command in, and have it spit out the PNG in the web interface. This would allow customized graphs (i.e. multiple storages drives on different devices, or combined Munin graphs) to be referenced in a dashboard or external link.

I’m not suggesting a new polling or data collection method with the ability to graph it. Just a way to build on what’s already in rrd files. Although this may provide a stepping stone for those who want additional functionality.

I may give it a go when I get some time. Until then I wanted to throw the idea out to the community in case it’s helpful, or someone is feeling ambitious.