For example, given a route between Miami and New York (driving), I’d like to figure out the lat/long of a location along that same route after some number of KM
This is possible with Google Maps extensions but i could not find a solution with OpenRouteService
GoogleMaps extension; Google Maps API Tutorial & http://www.geocodezip.com/scripts/v3_epoly.js
demo : Google Maps JavaScript API v3 Example: Directions Waypoints (LatLng)