What you’re asking for is fairly unrealistic. The only way this could work sustainably would be for something to exist where you host your own tile server and routing service and patch that into OSM. Otherwise, even if the app itself is open source, the backend will cost money to run and will be proprietary.
The reason that OSM is able to be fully open source is because you host the tiles on your phone and do the routing calculations locally.
It costs money to host something like that. You want low latency, real-time routing and tile-rendering? Even more money. Sure, it could be funded by donations or something like that, but I’m not holding my breath.
What you’re asking for is fairly unrealistic. The only way this could work sustainably would be for something to exist where you host your own tile server and routing service and patch that into OSM. Otherwise, even if the app itself is open source, the backend will cost money to run and will be proprietary.
The reason that OSM is able to be fully open source is because you host the tiles on your phone and do the routing calculations locally.
I can’t think of any reason the backend can’t be open-source too.
It costs money to host something like that. You want low latency, real-time routing and tile-rendering? Even more money. Sure, it could be funded by donations or something like that, but I’m not holding my breath.
Could be self hosted
If you’re willing to spend all the money on setting up and running a server, why not just spend way less money to get more phone storage and use OSM?