Leetcode seemed applicable. I got a question on a FAANG interview that was one that I was still puzzling over on LC. I recommend doing the blind 75, and really looking at the FAANG interview itself like a technical problem to be solved. In my case, the sourcer reached out to me, and I started studying, doing 1-2 leetcode problems after work for the month between that and the interview.

As for linear algebra and advanced statistics, I studied the matrix proof of Binet's Formula, but it didn't come up, and I've not had any statistics since AP in high school. Lin alg is super useful, and I've never regretted knowing that stuff anyway.

The people who study 8 hours a day for 6 months and the PHD's failing them are doing something hugely wrong.