Hi @h-koga
Which version of Office are you using?
The 'Get External Data' group has been replaced with "Get & Transform Data" group in Excel for Microsoft 365 Apps and other newer versions.
We are unable to find the corresponding command bar IDs to disable buttons in "Get & Transform Data" group.
Besides, there is no such GPO policy to disable features of "Get & Transform Data" or Excel Power Query.
As far as I know, we can disable the external content in Excel workbooks, the reference link is: https://support.microsoft.com/en-us/office/block-or-unblock-external-content-in-office-documents-10204ae0-0621-411f-b0d6-575b0847a795
Thanks for your understandings.
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