Complete Mobile and Web PWA App for Marketplace - Final Stages

I need an experienced developer to complete the final stages of my marketplace project. The tasks include integrating with the payment gateway, completing the buying, selling, and ad publishing processes, implementing full shipping rates and agent configurations, finalizing backend development, uploading APKs to Play Store and App Store, and ensuring real-time notifications and geolocation are working correctly.

Additionally, there needs to be an AI chat functionality for level 1 self-responses, with escalation to level 2 for human interaction if needed.

Key skills required:
- Flutter
- Node.js
- Applications development
- MariaDB
- PHP
- CodeIgniter
- API integration

Looking for someone reliable who can deliver quality results promptly.