Change admin panel and application roles

I have two Flutter apps for shopping offers that have been inactive for about a year.

I need someone to replace their admin panel with one I created.

I also need changes to the app:
- Remove the payment gateway: when clicking "buy," the purchase should be made without going through the payment method. It should just display a warning message before making the purchase.
- Limit the number of purchases; a user can only have three active purchases at a time; to buy more, they need one of the offers to be validated.
- Change the way the platform calculates the distance between the establishment and the user's location: It's currently expensive, and I need this changed, perhaps by latitude or longitude.
- Add a new button that redirects to an external page; when performing an action, it returns to the app.

I also need someone to provide me with the codes and help me submit the apps to the Apple Store and Play Store.