Has Google ever incorporated any of this site's code examples into its own products?
Only Google Knows.
That's a fair answer. Based on my morning's nightmare, I should like to think it was Google, and not something even worse.
Google has tons of excellent programmers and they don't have any need to use userscripts which are small code snippets for some limited purpose like extending/modifying small aspect of an already existing site. There's absolutely nothing useful/needful for Google in userscripts listed on any site.
Has Google ever incorporated any of this site's code examples into its own products?
Wondering.