I modified freeRoutiing to allow it to be used from the command line, batches and makefiles. It should be possible to make an addon to call it directly from KiCAD.
It uses the already existing -du to load the file. Then the extra command line options to route and exit after a number of iterations of the optimizer.
Add the parameter -asx Autoroute Save eXit when set with -du will load autoroute, save and then exit.
Add parameter -moi Maximum Optrermisation Iterations.
I don’t have time to create the addon myself as I’m starting but it is all uploaded here.