Game Slideshow Screensaver

Love that we can customize the screensaver to include screenshots, except I’m still pretty new to the Steam ecosystem, and have no personal screenshots to use.

Is there a way I can download external images to use on the game slideshow screensaver?

I’m feel like there is, but I’m having a hard time navigating through the Linux desktop to find the folder to save the images I want.

Is there a specific image file type I should be using? Or resolution? Is it possible to use a GIF? Do any of you have a pre-saved folder/image dump/website you would use for the game slideshow screensaver?