decky-steamgriddb VS SDH-FreeGames

But if you've got Deckyloader installed there's also this plugin to change all the artworks from within SteamOS as well.

It only automatically downloads images if you add them as a shortcut with the plugin. If you want something just for the images, there is an official SteamGridDB plugin like the other comment said. That plugin also allows for much better control like choosing from a selection of images and such.

You can install Decky and the SteamGridDB plugin to make the Steam integration look pretty.

There is a decky plugin that allows this (and more) in game mode. See: SteamGridDB

You can use Decky and the plugin for SteamgridDB to customize the logo, cover, header, etc.

If you install the SteamGridDB plugin through Decky if you have it, you can easily add all the game art to custom games.

Easiest way is with this. "Hero" is what you need to download the image for.

There's a plugin for Decky that can search through Steam Grid within the native steam menus and auto apply them without having to go to desktop mode, I use that and it's amazing. I did link to it's GitHub but it is also available in the Decky store page thing

I looked at Decky store and don't immediately see anything what would achieve the goal. I think https://github.com/WerWolv/SDH-FreeGames plugin looks like the closest thing to what I want, so if there is no already available solution, I think it should be possible to change the text in this plugin and the timeouts so that it sends notification with some predefined text every couple of minutes. But I don't have Decky installed, so I haven't tried it yet, maybe it doesn't work at all.