Microsoft never updated the Image Browser after 2010. It was slow (rendering 1080p images took seconds), lacked social features (no comments or likes), and was overshadowed by the Netflix app. Yet, it predicted:
: Pull out specific files, such as patched executables or individual assets, without extracting the whole 7GB+ image. Where to Download xbox 360 image browser download
Through the Internet Explorer app (added later in the console's lifecycle) or the Xbox Live Marketplace, users could download official wallpapers, dashboard themes, and gamer pics to customize their interface. Personalization and the Dashboard Legacy Microsoft never updated the Image Browser after 2010
You can typically find the download for on community-driven modding sites like Digiex or ConsoleMods Wiki . Step-by-Step ISO Extraction users could download official wallpapers
Your console already has one: