How does one balance career growth in the company AND prepping for interview at FAANG+?

I'm not L6.

But I did have to prep when I had a full time job and landed a mid-level role.

I basically sacrificed my evenings and my weekend to do 1-5 hours of prep a day.

I was able to find a community to do this with so it wasn't a straight grind AND I wasn't on a strict deadline. I would say, it took me maybe 6-8 months to land my offer (I took breaks in between). I was also very picky with the companies I interviewed with, as it sounds like you will be.

I was aiming for consistency and progress over optimization because that's too much pressure for me.

Finally, I also exercised passive strategies like networking with others, really tailoring my application to each position and coming up with supportive materials.

I hope that helps with your first question, I don't know what your schedule is like but if you share more detail, I can provide more about how I went through my journey.

Good luck!