Selecting a custom ellipsoid as reference

Hi everybody, I’m Alessio and I’m new to the whole Cesium environment. I’m actually developing a model of the Moon on Nvidia Omniverse using Cesium and data from Nasa missions (digital elevation map and images of the surface taken from here SVS: CGI Moon Kit ).
I’m actually having trouble uploding my models to Celsium Ion, since the only reference models for height are related to the Earth ellipsoid. Is there any way to define a custom ellipsoid as a referende? Do i have to use a different pipeline for getting to the desired result? Thank you!