Akaflieg-Freiburg/enroute ? reverse-engineered prompt

Build me a free flight navigation app for VFR pilots that works on Android and iPhone, and if it makes sense, also on Linux desktop.

I want it to help a pilot find their way in the air, with a map, current position, route planning, airports and waypoints, and a clean way to follow the flight while moving. It should feel simple and reliable, with a polished mobile friendly interface, good offline use, and privacy first behavior with no user tracking or data collection.

Please make the app usable end to end, not just a demo, so someone can open it, load flight data, plan a trip, and navigate with it. Keep it open source and non commercial in spirit. If you need current docs or aviation data sources, look them up online first.