I believe you need to follow below steps.
1. Deploying a metastore in one region.
2. Linking each workspace (from different Azure subscriptions but same tenant and region) to it.
3. Then validating that metadata objects like catalogs, schemas, and tables are accessible across all linked workspaces.
With these steps you will be able to provide a proof that you can access all the UC's across workspaces under the same metastore.