Personal Flutter Mobile App Development

Looking for a Generic Software Framework with
- Full Source Code
- Well Documented (Classes, Functions, Data Flow, Configurations)
- Highly Configurable (Content, Control Options {dropdowns etc.})
- Highly Extensible (add more pages, extend payment gateways)
- Ready To Use/publish
- Compatible with
o Web (Browser (latest version of Microsoft Edge and Chrome))
o iOS
o Android
- Available to install in
o Google Play Store
o App Store
- Payment Gateway Integration with Security