PCIe in Xavier NX

Hi, I am trying to design a custom board that can house the Xavier NX. I want to interface a standard mPCIe SSD and an mPCIe 802.11AC wifi module as well. This was not possible due to the presence of a single mPCIe bus.
But, the datasheet of the Xavier NX states that PCIex4 supports both Root and endpoint operation, while the PCIex1 supports only Root Port operation. What is the difference ? Is there any points I need to keep in consideration when designing this system ?

A root port is what you would associate with a “normal” PCIe bus where you can connect and detect and use devices. An endpoint is the reverse…using the Jetson as if it is a device when connected to another CPU’s PCIe bus. Think of a shared bus environment for multiple computers sharing over PCIe. Unless your PCIe bus is to be tied to another (external) PCIe bus without intervening bridge hardware to adapt, then a root-only port is exactly the same as the one capable of both root or endpoint operation. A “root” mode is the “normal” mode.

As for your use case, root port mode is for that. Just need to follow the DG to make the design.