The query Dataset... allows you to search by dataset type, so PDF vs AutoCAD. Does this not work for your situation?
Yes thank you, it was only easier than I expected :smileyvery-happy:
And is it possible to limit the query so to search only inside a specific Folder?
Not with any OOTB query that I know of.
You can select expand the contents of the folder, select all, show in details tab and filter by dataset type.