Trying to make a USB-HID keyboard using a MEGA/Nano

I have an Arduino Mega and 3 Nanos. Is there any way I could use these to make a usb-hid keyboard?

I have like 12 sanwa buttons that I want to use as a button only fightstick, but it'd work as a keyboard essentially.

Look at one of the many HID topics in the forum.

I have an Arduino Mega and 3 Nanos. Is there any way I could use these to make a usb-hid keyboard?

Forget the Nanos for this, the Mega might be used as it's USB coprocessor (ATmega16U2) can be re-programmed to act as a HID keyboard, although that's definitely no task for an Arduino beginner. I strongly recommend to buy a Leonardo (or Micro) as it's main processor (ATmega32U4) handles USB directly and you can program the HID functionality using standard IDE features.