Permissibility of working at Advisory Boutique Investment Banks

Assalam wa alaikum. My name is Umair and I have a question regarding the permissibility of advisory boutique investment banks.

Based on my previous understanding, I thought that working for Advisory Boutique Investment Banks that are focused on M&A such as Lazard, Moelis, Evercore, etc. were allowed. Additionally, I know that working for Bulge Brackets and Middle Market Bank as a traditional investment banking analyst is haram since they provide capital markets service that often entails DCM. However, I realized recently that a good portion of these Advisory Boutique Investment Banks that provide M&A service also provide restructuring for their clients.

I have a few questions regarding this. Does having an Investment Banking job that entails restructuring make it impermissible by default? Or can it be permissible if the main role is M&A advising? Is an Investment Banking job only permissible if it is for an M&A only boutique? Is working at a bulge bracket or middle-market bank as an ECM Analyst halal? I’m at crossroads right now as an incoming college freshman and I’m not sure if I should just make the hard but potentially necessary decision of quitting my pursuit for an Investment Banking Job since there are very firms that are M&A only.
Thanks in advance!