I would really like this also coming from Evernote where PDFs can be viewed inline. I write scientific papers and most of the figures are best stored in PDF format. I think that this should be a core feature - not handled by e.g. iframe embeds especially since electron has this capability. For performance reasons it should have the option to disable inline PDF renders though for people who do not want it.
I do not see the “Feature Request” tag on this post, could it be added by the mods? I did not see an existing feature request that overlaps with this.