PCIe Gen4_PCB Material

Hi,

We are planning to use a M.2 module with PCIe Gen4 (Only Single TX/RX pair).

We have terminated PCIe Gen4 from ORIN to M.2 with zig-zag routing as mentioned in the design guide.

Can we proceed with the standard FR-4 PCB material for the above config, since it is a single PCIe pair and routed length is only around ~40mm?

Or do we need to change the PCB material similar to the ORIN devkit (spread-glass) mentioned in the FAB note?

Any suggestions on this.