Flutter AR Geo-Spoofing Prevention

We are working on an app built with Flutter, with a Node.js backend, and the server is hosted on Contabo. The current problem is: If a user is physically located in the USA, and the reward system on the... (Budget: $250 - $750 USD, Jobs: API, AR / VR 3D Asset, Augmented Reality, Flutter, Linux, Node.js, PHP, Ubuntu)