Flutter work on existing App -- 2

I have an app that needs some bug solving(4-5 main bugs) and some new functionality. I will provide all APIs and will provide guidance about the API's. These functionality has already been done on our website and we just need to implement the same on the App.
Here's a list of new functionality:
Video Uploading LMS
Notification Bug(This notification is with sound and plays according to an API
Sign up with Social Google and Facebook
Donation
Invoice(From API. In App this needs to just download the generated PDF)
Tasbih - Small Animation
Forums (From API)
Masjid Finder
Should able to share any component on social media (with /without image)platforms with image
calendar update from API.
Quiz(From API)
Live Makkah video feed(You Tube feed)
Separate form for free classes(Simple form based on value from API
Functionality similar to https://webdesign-commercialexperts.co.uk/Apply