I think GitHub activity can be used to see how active the devs have been, but I doubt it can be used to see how much progress has been made. If all activity went into adding a few spaces/dots and that is registered as activity, there is room to 'game' this system. 

You'd have to dive into the commits to see what was added in order to determine if it has actual progress, or go with what the dev team puts out in writing detailing what they have completed ;-)