Flutter Sports Social App | MUST PASS Offline GPS Background Tracking Demo Test firstly

We are building a sports and chatting app focused on online connecting users with workout partners (hiking, running, etc.). ** NON-NEGOTIABLE FIRST STEP (Please Read Before Applying) To ensure we are a match, we require a small, verifiable proof-of-concept before discussing budget or timeline... (Budget: $3000 - $5000 USD, Jobs: Android, Backend Development, Flutter, iOS Development, Mobile App Development, Mobile App Testing, PHP)