Overall picture: Google recognizes it's a large company that has an extreme diversity of teams with idiosyncratic goals and personalities, and doesn't prescribe _anything_
Dollars to doughnuts, there's multiple teams doing extremely prescriptive Agile, but I've never seen one in 3 years in a 2,000 employee office.
By far the most organized team I've been on merely kept track of bugs using an internal web app that renders bugs from the internal bug tracker as post-it notes arranged in columns, with each column representing a bug status (ex. assigned/started work/code in review/done).
This alone caused a ton of grumbling, meanwhile I'm sitting there gobsmacked that Scrum and Agile aren't proper nouns that everyone has highly detailed opinions on.