Inverse: pedestrian shortcuts

https://www.openstreetmap.org/way/671146174 as a motivating example.

Look for a driving route between the endpoints of a footpath, and calculate the detour ratio. High values are better pedestrian shortcuts. (Complications include having to take into account all the complexities of driver routing, like turn restrictions and which direction to do the routing. And even in this example, both endpoints of the footpath aren't driveable -- have to search further on the graph.

An analogous route / score mode would be helpful. And showing both scores in one place could be interesting, to find areas favoring one mode.