In many cases they don't. I'm a PM at FAANG but the process is roughly similar in that you do a generalist interview loop. Most PMs work on consumer products so the questions are commonly stuff like [highly simplified for example purposes] "how would you grow the userbase of a new photo sharing app" or "Which is more important, growth or retention and why?"
I have some colleagues who are career enterprise and infrastructure PMs and they tell me it's very frustrating to have tons of very valuable expertise and then get asked a question about Tik Tok in an interview. I've also heard from SWE friends that they self-identify as a backend/infra engineer to the recruiter, only to show up to the interview and be asked to create a webpage from a mock and some specs. tl;dr FAANG has not figured this out yet.
I have some colleagues who are career enterprise and infrastructure PMs and they tell me it's very frustrating to have tons of very valuable expertise and then get asked a question about Tik Tok in an interview. I've also heard from SWE friends that they self-identify as a backend/infra engineer to the recruiter, only to show up to the interview and be asked to create a webpage from a mock and some specs. tl;dr FAANG has not figured this out yet.