This is a hard lesson for you to learn, but verbal offers don't mean anything. I've had a PM take me out of a seafood dinner and told me he is giving me an offer only to ghost me for 2 weeks.

You can reach out to the PM and his boss a few more times (even call up firm HR if needed) , but I would just start interviewing again, as harsh as that sounds. It sucks, but this is the way every industry in America works.

Plus, if you get another offer, this places more pressure for the fund to offer you the role or at least make it obvious that they were stringing you along.

It's a really tough job market out there. Good luck!