Flutter Developer Needed for VPN App with mySQL or SQL Server

I am looking for a seasoned Flutter developer to build a VPN app for me. The application needs to have a solid backend, so knowledge of MYSQL or SQL Server is crucial.

Backend
1. User signup with random username and password api
2. Get user detail api
3. Get a premium plan
4. Buy premium by user
5. Referel point update for the user
6. If require payment gateway api

Frontend
1. Api integration
2. Payment gateway
3. Referel code submission
Payment in RMB and USDT is required, with Chinese software

Thanks