Curious to hear any recommendations for a pdf viewer which can display transparency in PDFs without just setting the background to white.
I am currently using evince, which does exactly this as far as I’m aware. And from what I can see it is not something I can change either.
I think okular does which i have on kde.
Edit: Keep in mind in pulls in a lot of packages on the installation. Not sure what desktop you are using?
Using gnome so no helpl there 
Okay zathura is the one you might want for Gnome.
Edit: I would likely try zathura-git
Are you sure okular can, I just tried and it doesn’t seem like it’s able to either.
Do you have a sample pdf with transparency you can share?
I didn’t think you were going to try it on Gnome because it has so many packages it installs? I see zathura maybe is a better choice for Gnome.
Edit: @dalto would know better on this. 
I tried it anyway, figured I could just remove everything if it didn’t work
@dalto I just checked in adobe on my windows partition, the background of this should be transparent. example.pdf (6.8 KB)
qpdfview seems to support it. It has a setting for “paper color” which defaults to white although you can change it to whatever you want.