Modder ‘RoseRosenberg’ has released a new version of is Fallout New York mod/unofficial expansion for Fallout 4. As its title suggests, this unofficial expansion will be based on New York and the first priority is to create the city around Central Park which will be closed for the moment.
Naturally, this current version of Fallout New York does not represent the quality of the final version. The entrance for New York is on Memory Den with a door (for the moment) and in future versions the city will be modified to be more destroyed with exploring places and enemy camps.
In its current state, this unofficial expansions is updated on a monthly basis and does not currently feature navmesh, quests or a road.
Those interested can download the latest version of Fallout New York from here.