I want to modify, fix, and enhance code written in Flutter with Firebase.

I want to modify, fix, and enhance code written in Flutter with Firebase.
Fixing and developing the code according to the instructions and ensuring the following features: when the stream owner enters, a notification is sent to all users. When any user is added to share, a notification is sent to all users. When any user comments on a post, a notification is sent to the post owner. Adjusting the payment method and linking it with PayPal. Adjusting the free period and changing it from free to paid. Fixing and modifying adding a post according to the video instructions. After watching the video, attention should be paid to other matters. Ensuring its upload on Google Play Store and ensuring its proper functioning by linking it with Firebase databases. Ensuring its upload on Apple Store and ensuring its proper functioning by linking it with databases. Ensuring its addition and linking with AdMob advertising program and ensuring its proper functioning on the store.

flutter - firebase
see full
https://youtu.be/cxYcBq43yiM

the code

https://github.com/kulwinder1595/streaming_post_demo