GPRS Charity Ride Tracker

I’m planning a charity bike ride for April and need a clear estimate to build a lightweight GPRS-based tracker app that works on both Android and iOS. The core requirement is reliable, real-time location sharing so supporters can watch our progress live on a map throughout the ride.

Everything else can stay minimal for now: route history or geofencing can wait, and user accounts are optional—if you propose a simple guest mode with a private ride code, that’s fine. I mainly need to understand the cost, development timeline, and any technical considerations (server setup, map APIs, battery usage, data traffic) for delivering a polished, store-ready app before the event.

Please outline:
• Your recommended tech stack (native, Flutter, React Native, etc.)
• A rough breakdown of stages with estimated hours or milestones
• Any recurring fees (hosting, map tiles, push services) I should budget for

If you have examples of previous live-tracking apps, feel free to include them so I can gauge complexity and refine the feature set together.