How can I better prepare for a new role?

Honestly, my advice here is to just chill as much as you can. Working at Big Tech is usually stressful (especially as an L6 engineer), so you might as well take this month to clear your mind and really head into the next job with a fresh start. Job switches don't happen too often, and not relaxing enough during those "in-between" period is something I have always messed up and now regret. 😅

FAANG companies are all huge and have extremely custom stacks, so there's not much you can do to prepare technically anyways.

Something I do recommend trying though is building up the relationships early (try connecting with your future coworkers on LinkedIn). I actually wrote a checklist for this that you can follow in this other discussion: "What's the best way to prepare 'before' joining the next team/company?"

How much do you know about the product and priorities of the company? If you can talk to the people at the new company in a casual way, you can start to understand this and build that understanding.

Equally as important is to understand the teams and people behind the projects you'll be working on. I don't think there's much you can do before you join, but building deep relationships is very important when you start.

I don't think there's much value in trying to anticipate which tech you might use and prep for that. If you're joining Big Tech, you will use a bunch of different tech, and it'll be a different flavor from what you might get "in the wild". If you are rusty on things like version control, you could spend some time on that, but this is not the highest leverage thing you could do.

In addition, as a Staff engineer, your code velocity becomes less important relative to your ability to set direction for the whole team.

Oh yeah, and don't forget to relax! You want to be excited when you start your first day, not burned out and stressed. Companies will give you at least 1-2 months to ramp up.