Graphhopper Navigation SDK for custom maps

Hi all!

I am currently entering my final year of college and for my final presentation I want to build an android app for the local zoo in my hometown. In said app I would like to include a map of the area where the zoo is located and add to it the layout of the zoo itself(walking paths, attraction locations etc) so that the users can use the turn-by-turn navigation feature in the zoo itself. So far I have set up the routing using the OSRM backend docker image, and I have the map file itself as an *.osm file which contains the roads for the zoo. I tested and the routing engine does return directions using roads within the zoo under a GeoJson format.

I am now wondering if it is possible to integrate these directions, from my custom OSRM backend, in the Graphhopper Navigation SDK. Maybe if there is a way to bypass the use of the Directions API. So far I have tried to work with Mapbox by passing the GeoJson to the DirectionsResponse.fromJson() yet the route they display does only go as far as the entrance to the zoo(basically does not take in consideration my custom roads which do not exist in the OpenStreetMap data).

I was thinking to add the zoo layout to the OpenStreetMap but I am not sure of the legislation issues so I would like to keep this project data private.

One thing that is worth mentioning is that I have rendered the OSM file and currently I am hosting it using MapTiler cloud.

If you have any suggestions, I would greatly appreciate it. I am a newbie to developing android apps and it is my first time working with geospatial data! Thank you for your patience and understanding!