BOM: https://developer.nvidia.com/jetson-xavier-nx-developer-kit-carrier-board-bom-p3509-a01
compliance: https://developer.nvidia.com/jetson-xavier-nx-developer-kit-regulatory-and-compliance-documents-p3518
carrier board spec: https://developer.nvidia.com/jetson-xavier-nx-developer-kit-carrier-board-specification-p3509-a01
user guide: https://developer.nvidia.com/jetson-xavier-nx-developer-kit-user-guide
supported componets: https://developer.nvidia.com/jetson-xavier-nx-supported-component-list
I hope you may find what you want.