@Pete,Thanks for posting in Q&A.
Based on my research, I didn't find the rule to create the dynamic device group according to the owner.
https://learn.microsoft.com/en-us/azure/active-directory/enterprise-users/groups-dynamic-membership
But I find the following link mention that the physicalIds field in Azure AD contains USER-GID information. And you can build a dynamic query on that. You can try and see if it can help
Hope the above information can help.
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