There currently is no way to export a project to the App Store from within the App. There is no app in the App Store that can do this. In order to get an app to the App Store, you have to use a MAC, have a developer account, and use Apple's Xcode
Here is what you do:
Build app in Pythonista
Export to Dropbox
Download the Xcode project template to your MaC computer
Set up a developer license with Apple (99$ a year)
Download Xcode
Put Python script and template together in Xcode and build app to submit to App Store
Like it or not. This is the process. It's not perfect, but the road to App Store success is bumpy😉