yeah the emmc is the same board shape and connector.

just go to ifixit for the ssd swap guide. don't peel the shield though slide it off instead. if it doesn't go in easily try from the other side. I put it in from the side with the cutout for the screw and used a plastic spudger to lift the cutout edges over the new ssd.

Before all that get the steamos installer ready which can be done from desktop mode. you need a usb drive which needs to be 8gb minimum to flash the image and if the drive doesn't have a usb-c plug, either an adapter or a C to A hub. I couldn't get balena etcher to run on my deck so I just used dd from the console. If you install new ssd first you will need another computer.