@Krishna Chandrapati, Thanks for posting in Q&A.
Based on my test, I find the "Add store app" is only available to add the Microsoft store for Business app. For the new Microsoft Store apps, it is not supported yet. You can feedback to Intune uservoice to see if we can add it in the future.
https://feedbackportal.microsoft.com/feedback/forum/ef1d6d38-fd1b-ec11-b6e7-0022481f8472
Thanks for your understanding.
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