Hello,
I am looking forward for the PCIe specification support for the Orion Nano Module. While exploring the site, I got that it only support Gen3 but datasheet specifications show the support of Gen4 also. I am attaching the image for the reference.
Link for the product specification guide- NVIDIA Jetson AGX Orin
Sometimes, there is a difference in HW specification and SW support available . Although, a feature could be supported in HW it is limited by SW. SW support is limited for PCIe to Gen3 on Orin Nano.