Very cool! It's a bit off topic, but I used to enjoy Google's travel app, which had a feature that found the shortest path between many popular tourism destinations in a city. That way as close as I'll personally come to route optimization ;)
By the way Routing24 works on mobile, optimizing when offline too. It's just the current app is designed for desktop and route planners. Solver itself works on any 5 y.o. brick with shattered camera like a charm.
btw: thanks for using photon for geocoding ;)
Currently distance/duration matrix is built server-side yes. Eventually this part will be fully local too.
Working on "tiled" CH first and then CCH. I haven't even investigated patent and license situation around customizable contraction hierarchies yet.