It was indeed broken, fixed now.

If you decide to actually go for it, in order to get it to compile I did something like this:

nix-shell
mkdir build && cd build
cmake ..
cmake --build . -j$(nproc)
wrapQtApp bin/CarNavigation
NIXPKGS_QT6_QML_IMPORT_PATH=/nix/store/66hlc66dkinbrc7ifq0v6ynaq3vkv35y-maplibre-native-qt-3.0.0/qml bin/CarNavigation

(I'm not sure why the wrapQtApp doesn't pick up maplibre, maybe it's something to do with the patches they apply, didn't have time to investigate. I also didn't have the time to investigate what is needed to get it "installed", hence to installPhase and nix-build doesn't work)