WLB not as important as Flexibility?

I'm getting close to FAANG offer or two at the tech lead/principal level (think E6 at FB, L6 at G). Currently a director level at finance company. What I really enjoy about where I am, even though finance may not be known for it, is the flexibility. By that I mean I work (and am happy to work) 45-50 hours on a normal week, and maybe 60 or even 70 hours on a very busy week. However, I never spend more than 30 hours a week in the office, e.g. I work at home 2 days a week and am there from 8 to 4:45...without exception. As the primary caregiver to two young kids (wife travels during the week) this flexibility is non negotiable for me. Truth is I could care less about what I consider "wlb". Quite the contrary, all I want to do after I put my kids to bed is log back on for a couple hours and work on some interesting problem. I love wfh days because it allows me to log in at 7:30 and continue up until 6. I don't want wlb, I want to spend my free time working! So obviously most finance companies aren't this accommodating, I have this schedule because my manager has known me for over a decade and knows the particulars of my work. In general I'd expect for example Facebook to be more flexible than JP Morgan, but people here say that FB and Amazon swe have no "wlb"'. So help me Blind, forgetting about wlb for a minute, how do these companies rate in terms of flexibility, particularly at the tech lead level? Current TC: about 300k, all cash