Hello Adz,
Thanks for reaching out!
As per my knowledge, there is no Graph API endpoint to retrieve the comments of a SharePoint site page using Graph API.
You may try to use SharePoint Rest API to get the comments.
/_api/lists/getbytitle('Site Pages')/items(pageID)/comments
Refer this similar post: https://learn.microsoft.com/en-us/answers/questions/326830/site-page-comments-extraction-in-sharepoint-using For latest updates/changes to graph APIs, you can refer to this Changelog Portal. Hope this helps. If the answer is helpful, please click Accept Answer and kindly upvote. If you have any further questions about this answer, please click Comment.