Cross-Platform Mobile App for Field Service

I am looking for an experienced developer to build a cross-platform mobile app for our field service team.

The app will be used by technicians to manage assigned jobs while they are on-site. The main requirement is that it should continue working when there is little or no internet connection and automatically sync data when the connection comes back.

Core requirements:

Flutter app for iOS and Android
User login with role-based access
Technician job list and job details
Create/update job status
Offline data storage and background synchronization
GPS location capture
Take and upload photos from the job site
Customer signature capture
Push notifications for new or updated jobs
REST API integration with our existing backend
Conflict handling when offline changes are synchronized
Basic activity/history screen
Secure local storage for sensitive information

The backend API is already available, so the main focus is the mobile application and reliable synchronization.

I’m particularly interested in developers who have previously built offline-first Flutter applications, field-service/workforce apps, GPS-based workflows, or applications involving background synchronization.

Please include one relevant project you've actually completed and briefly explain what you built.

The first version should be production-ready rather than a prototype. I’d prefer someone who can take ownership of the technical implementation and help identify potential issues before development starts.

Please provide your estimated timeline, availability and fixed-price estimate.