From the create and manage submissions using Windows Store services, we can see that you can use Windows Store submission API to get data for existing apps in your Dev Center account.
Please note: This API can only be used for Windows Dev Center accounts that have been given permission to use the API. This permission is being enabled to developer accounts in stages, and not all accounts have this permission enabled at this time. To request earlier access, log on to the Dev Center dashboard, click Feedback at the bottom of the dashboard, select Submission API for the feedback area, and submit your request. You'll receive an email when this permission is enabled for your account.