Help needed to trigger wakeup using button

I use the button on the Giant board to boot it up after a shutdown.

On CrowdSupply ( the available low power modes are mentioned and explained.

While I had no problems using the RTC to wakeup from a suspended state, I have not figured out yet how to achieve it using the On-Board button or the PW-ON/EN pin (The silkscreen on my board says PW-ON while the pin is called EN in this image:

I would really appreciate if someone is able to tell my which device tree overlay is required.