You don't get much in the way of choice for screensavers by default with Kobo, even with a different affiliate. You've got the option of a fairly blank screen with reading stats for your currently read book, or the cover of that book with or without the stats.
However you can tweak it so you can have your own images as screensavers.
https://www.mobileread.com/forums/sho...d.php?t=255238 will get you there. You wont be able to select a single image unless you only load one image.