Has anyone done the product architecture interview at Facebook? This is for Software Engineer - Product, E5/E6. I have 2 product architecture interviews planned and apart from the information on the facebook Onsite Interview Guide page, I don't see any other information out there. Does anyone have any sample questions other than the ones given below:

• Design a service or product API
• Design a chat service or a feed API
• Design an email server

And what is the focus really on? There's a ton of information on the system design interviews, but unfortunately not much on the product architecture interview. Any sample questions would be really helpful.