At this time, the ability to make images from every single page of a PDF to insert into emails is not on our road map. This is partly a best practice aspect - we do not recommend sending image-only emails, as well as a deliverability issue - image-only emails tend to result in higher rates of spam filtering and bounces. There are other factors, but those are two of the most significant.
If you're needing to convert your entire PDF into a series of images, it's recommended you utilize an external site, or the program used to make the PDF, to do so. Then you can upload those individual pages' images as any other image. I would also recommend checking out this Community Blog post for some more info and advice.
If there's an update in this idea's status with the devs, we will update the thread accordingly.
