Scoped scan can be done only on catalog level. So, you might have to try splitting the catalog and modify based on your requirements to minimize the scan volume.https://learn.microsoft.com/en-us/purview/register-scan-azure-databricks-unity-catalog?tabs=MI#known-limitations
For governance, you can try automation/script to looks for tables as per your requirement, this will still not limit Unity Catalog Scanning.
For tracking you can try lineage: Introducing Lineage Tracking for Azure Databricks Unity Catalog in Microsoft Purview
Hope this helps!
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