RZ/A1 RSK Linux GPIO Mapping

I'm investigating the RZ/A1 using the RSK+ and want to control an external switch with a gpio. Within Linux, nothing is exported for GPIO by default with the BSP.

$ cd /sys/class/gpio/
$ ls
export gpiochip0 unexport

I've been looking at the schematic in an attempt to map pins there to gpio numbers within Linux:

https://www.renesas.com/en-us/doc/products/tool/doc/003/r20ut2586eg0300-rskrza1h-board-schematics.pdf

How can I map the GPIO? How do I figure out, say GPIO 25, corresponds to Pix ABCXYZ in the schematic?

Thank you.