It really depends on how they level you, which you won't really know until you engage with them and interview. It's less likely you'll be presenting at conferences and writing articles on what you're doing at Facebook, though not impossible.

Work/life balance isn't as good as other FAANG, but not necessarily awful, though it depends on team. There seems to be good leave and a general support for parenting and family responsibilities, but I can't speak too well since I'm not a parent. If you learn about their parental leave, that should give a reasonable idea of how they value parenting.

If you don't think there's an amount of money you can get paid to not be the "biggest fish", then it may just be worth getting an offer to request a raise at your current company. Regardless of how you feel, I think it's totally worth interviewing with Facebook, to learn about the company and what they value.