I doubt Node.js is going to fly, as it is a complete nightmare from a distribution packaging perspective. Also, anything that requires network access in the GuiVM is a non-starter.
GNOME shell support requires client-side decoration (CSD) support in the GUI daemon, meaning that the GUI daemon would itself draw the window borders without relying on the desktop environment. This would make Qubes able to work without any explicit support from the desktop environment and without creating a security vulnerability. As such, it is a worthwile feature in its own right. That said, it is not sufficient for proper integration; see the linked thread for details on that.