Hi OCD77 Ephelios,
To cross-reference Intune mobile hardware properties against an external corporate manifest, you cannot use native Intune Device Queries because they cannot ingest external files. Instead, you must route Intune inventory logs to an Azure Log Analytics Workspace via Intune Diagnostic Settings. Once the data streams into Azure, you can use a Kusto query with the externaldata operator to pull your procurement manifest from a secure Azure Blob Storage URI and perform a left outer join against the IntuneDevices table, allowing you to instantly isolate and flag unauthorized serial numbers, IMEIs, or SIM cards.
Hope this answer has brought you some useful information. If it did, please hit “accept answer”. Should you have any questions, feel free to leave a comment.
VPHAN