How's Core ML Ads team at Meta

I am joining in a few months. I was contacted by a hiring manager for the Core ML ads team. According to the meeting we had, the work is super impactful. They own most of the important ML models powering ads across several platforms. They also focus on the model architecture/ core ML and not really on pipelining and feature engineering etc. So the work in itself seems very interesting.

Is anyone familiar with the team? My concerns are that being a well-established team (even though they are growing a lot according to the manager) There are no low-hanging fruits and showing impact is going to be hard.
Also, how is WLB? Not that it matters much for me as I prioritize growth but it is nice to know.
I will be joining as E4, how hard it is to make it to E5?
I won't be choosing now anyway as I will be going through the BootCamp but it feels that the team is a great opportunity and wanted to know how others at Meta felt about it