You wear pink 👓 about G and you may be too idealistic to admit it. Neither Google nor MS or most other tech companies in Bay area or Seattle have a strict dress code. And all interviewers go through training to tackle their biases and judge interviewee based on what is important not superficial traits. But humans are individuals. Wearing something that's completely off for everyday culture may have negative or confusing effect.
Interview feedback at Google is pretty structured, and there is not a place to score a candidate on their outfit. It could maybe affect other scores a bit if the interviewer is biased and the candidate's performance is borderline, but I don't think it would be a significant effect in most cases. And certainly if the candidate solves the problem well, they will get a good score even if they are wearing a suit.
I would recommend a buttoned down shirt with a nice pair of jeans. Also nice shoes. You dont want to appear too formal yet you dont want to show up like you just woke up either. A general rule of thumb is to be better dressed than your interviewer. Hope this helps!
As the old song goes, "if you come to San Francisco, be sure to wear a flower in your hair." Anything else is optional really. I've seen on a few occasions people walking naked in the street, in broad daylight.