I actually have this kind of working on a branch - really don't fancy hosting any infrastructure myself though - so I was intending it to be a Windows service or docker container you have to setup and pair with. Once you've done that - the endpoint is included in any group you create, and treated as an extra node in the graph. If available and lower latency than other routes, it'll be used.

Was trying to keep things simple though - the separate server seemed a step too far for most people I talked to about it.