PDF reader with thumbnail preview in the opening dialog

Situation: I download lots of PDFs which have unhelpful file names, such as arXiv papers (thanks, 1807.03042.pdf). I'm often reading one of them in Okular and want to switch to another, say just to look up a reference, but the file open dialog lists only the names so it takes some effort to find the right file. I'd love to have a preview pane there or just the first page thumbnail for each file. **Is there any PDF reader for Linux that has such a preview feature?** (I am on Arch if that changes things.) I'm aware that various file managers do that, but I was hoping to avoid running another app given that I just want to open the PDFs. I am happy to tinker with Okular's code as well (it uses Qt for the UI), but from my googling so far it doesn't seem like Qt has a magic "thumbnails on" switch, and would require actually writing the full previewer...