No, the 2TB memory will not act as normal GPU memory by default. The developer must implement specific API calls and support using the NVME volume as memory.
For instance, the recently released Adobe Premiere Pro version is the first application to claim to support the SSG. However, it still does not work using the latest drivers. There are some indications in the Adobe software it may do so in the future, with the new persistent cache option. However in my testing the option doesn't actually do anything.
So for the time being, with the SSG you get a wx9100 with a 2TB NVME drive bolted on.