[mmmm2]

It depends on the FAANG, though most of them have some amount of C++ code. Google has a ton; they'll appreciate people who know the language well.

I think people may be concerned because these days it's more niche, though it's still a very common language. Take a look at the job postings from the companies you want to join and see what skills they want. Get familiar with some of them, even if you don't do them professionally.

Get good at the Leetcode style questions.

Are you doing distributed systems work? Can you answer design questions like: design bit.ly, Twitter, or Facebook? There's a lot of info out there on how to solve these problems.

There may be questions about your ability to work with "big data". But that's also something you can pick up on your own, even if you aren't doing it at work.

Look for technically challenging projects at your job and solve them. Learn from them. Think about ways you could have solved them better with what you know now.