Hello Ashish Barnwal,
Thank you for reaching out.
There is no official documentation published yet to determine of when this feature will be available, however, you can keep your eye on the Microsoft 365 roadmap to get any update about this endpoint. https://www.microsoft.com/en-us/microsoft-365/roadmap?filters=&searchterms=Create%2FUpdate%2FDelete%2Ca%2Cregistrant%2Cfrom%2Conline%2Cmeeting
I would recommend you provide feedback to Microsoft UserVoice to this link;- https://feedbackportal.microsoft.com/feedback/forum/ebe2edae-97d1-ec11-a7b5-0022481f3c80
Hope this helps.
Thanks.
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