Since Non-Specimen Requests are not query able. You can use the 'Show requests without specimens' feature from request list view. 

• Navigate to the Project → View Requests → Search → Show requests without specimens. The requests which have no specimens added in the request are shown if you check the ‘Show requests without specimens’ checkbox. 

• On request list view the requests shows the number of specimens added in that request as below.

• You can export the report of these requests on filtering using 'Export' button. Attached CSVs for reference.