@Muckypaws I think you can do this with core input remapping.

For quick menu > controls > port 2 controls, you want to set the joystick directions to their right stick counterparts, and then set mapped port to port 1. Now the player 2 joystick should behave as player 1 right-stick. Save this as a game remap file and you should be all set.

https://retropie.org.uk/docs/RetroArch-Configuration/#core-input-remapping