Comment by karussell

For OSM-only data you could set up wheelchair routing with two commands (via GraphHopper) for the region of your choice:

https://github.com/graphhopper/graphhopper#installation

In the config you specify

graph.flag_encoders: wheelchair

and enable elevation:

graph.elevation.provider: srtm

It then considers elevation and many restrictions already but it is probably not as fine tuned as it should be. We would be happy to accept improvements.