Add functionality to app - Dart / Flutter app update

I have two apps - one is self service app and one we set up for the customers:

The apps are checklists which the user completes, the checklists are then recorded as reports.

SF APP ONE
- Add label printer which is already built in on 2nd app.
- Adding label reorder button synced to Amazon so customers can automatically reorder labels and their stripe - account is charge and amazon sends the label to their address.
- Add Subscription change to add the label subsctoption level and another + Multiple sites subscription which would have a high level dashboard to enable the owner to see multiple sites (they would be charged per additional site setup)
- Add delivery commments in delivery section on app which shows on reports also.

G2 APP
- Adding label reorder button synced to Amazon so customers can automatically reorder labels and their stripe - account is charge and amazon sends the label to their address.
- add manual label button in label printer part on app.
- Add delivery commments in delivery section on app which shows on reports also

Thanks