@Jeremy King, Thanks for posting in Q&A.
To upload a private Android app to the Google Play Store, you can use Microsoft Intune to add a Managed Google Play private (LOB) app directly in the Intune admin center [1]. The LOB app is then added to your private store in the Managed Google Play console.
However, if you are receiving an error message that reads "The package name is already used by another application", it means the package name of your app is already in use by another app in the Google Play Store, and you cannot use it. You can ask your app developer to try using a different package name for your app and try resubmitting.
[1] Add Managed Google Play apps to Android Enterprise devices with Intune. Retrieved from https://learn.microsoft.com/en-us/mem/intune/apps/apps-add-android-for-work#managed-google-play-private-lob-apps
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.