[echoangle]

If I enter Madrid and Milan in Google Maps and select walking, it does show some footpaths to take, no? Those don’t look like major roads.

Don’t know how to share the route without doxxing myself but you can enter it yourself.

[artisinal]

In the example I gave Google will tell you to walk over N340 / Via Augusta. Highly dangerous.

Walking Madrid to Milan Google suggests to walk here: https://maps.app.goo.gl/STmiz37BiKtxe6HX7

(41.9218388, 1.2047772)