I have a friend there. I sent him my CV and after a week or so a google recruiter reached out to me.
At first they sent me by email like 10 or so questions. I had to write the answer and then send it back to them. Questions were the typical stuff you would get in an HR interview. They focus on the languages you know and description of a project. SQL and R seem to be the main languages they look for, I knew it from my friend already so I heavily targeted my answers towards those.
After this, they assigned me to a specific team for the recruiting process. It was SMB ads.
Then they sent me a data challenge. Nothing particularly hard. I had to send it back within 3 hrs. There are a few online resources for takehome challenges and this was definitely on the easy side compared to what I used to prepare.
Then they booked my trip to SF for a 1 day of interviews. Lots of stat questions: estimators, different distributions, and linear and logistic regression in details. No puzzles, which surprised me cause I heard so much about google puzzles (I even bought and practiced so much on that wall street book).
I didn't get the job, but the experience was very positive. I think they look for statisticians more than general quant people with some stat knowledge like me.