It is not possible to use a single query to obtain all the profile photos and user data of all users in the group, and this feature is not currently supported.
Your endpoint in the question: GET /groups/{id}/photo/$value
is only used to get the group's photo, not the profile photo of the user in the group.
At present, you can only use GET https://graph.microsoft.com/v1.0/groups/{id}/members
to list the data of all users in the group first, and find the id of each user through user data, and then list each user’s profile photo by user id GET /users/{id | userPrincipalName}/photo/$value
.
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