@Gordon Oh Thanks for posting in our Q&A.
Honestly, I didn't find an API that can get unmanaged apps. Please note that graph issue is more related to develop scope. With Q&A limitation resource, it is suggested to create a Premier or Unified support ticket to get more help. Here is the support link:
https://learn.microsoft.com/en-us/mem/get-support#premier-and-unified-support-options
Thanks for your understanding and hope everything goes well with you.
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