On many APK indexing sites, "xnnn" often acts as a or a specific category tag for a wide variety of content. Depending on the context of your search, it generally refers to:

You searched for xnnn - AndroForever

: Users can download videos directly; the site also suggests using in conjunction for easier media management. User Feedback & Trust AndroForever

He wasn’t looking for anything special. Just a driver update for a piece of legacy hardware—a video capture card from the late 2010s. The kind of tech that was obsolete before it hit the shelves, now only useful to archivists and people like him, who dug through the digital graves of the internet.