I have a folder with hundreds of short Google docs (product descriptions). I am wondering if there is an easy way (like "push button") to export all these in a PDF that simply assemble all the PDF into one single document.
I believe there is no integrated Google Drive feature for that at the moment. Essentially what you are trying is exporting server-side merged files. What you could do instead is download all the files in questions (in PDF for instance) and merge them locally. There are applications like pdfsam that can help you do that.