I believe ownership would stay with him, as the Grantor of the trust, until he passes. 

I’m seeking advice from any investors who have dealt with the pain of owning a co-op in NYC.

It's important to start with some foundational education.1.

My son is the property manager, and house hacking with three roommates.

You can get a good feel by speaking with others.

I am not a W2 employee so constantly limited by my DTI when it comes to bank lending even though I am savvy with saving, house hacking, etc to keep my cost of living down.

I would love to connect with realtors & discuss local market knowledge, recommendations & overall support.

I'm exploring all options at this point including finishing the home with other builders, as well as selling what has been built (slab and block walls of a single family home 4 bed 3 bath) to another builder or investor.Does anyone have any recommendations on where to look for potential buyers for something like this?

I'm currently where you were at the time of your post, and would greatly appreciate if you don't mind sharing yours with me. 

can you start with a house hack?