The latter. NIMs is Nvidia's umbrella branding for proprietary containerized AI models, which is being pushed hard by Jensen. They build models and containers, then push them to ngc.nvidia.com. They then provide reference architectures which rely on them. In this case the images are in an invite only org, so to use the helm chart you have to sign up, request access, then use an API key to pull the image.
You can imagine how fun it is to debug.