Steam Deck is launching in Asia region, and to celebrate it, Valve revealed some earlier prototypes of the handheld gaming device which dates back to around 2019. All of the revealed prototypes are mentioned to be bootable, and they have the same configuration of buttons except the D-pad in some older models. Instead of the D-pad, they have segmented buttons similar to Nintendo Switch.

Another small difference in the older models was the circular trackpads rather than the square ones we see today in the current Steam Deck model. Last but not least, the thumb sticks were relatively smaller.

These prototypes were reportedly hand-built. The thumb sticks actually resemble the ones in PlayStation Vita, and the direction buttons resemble the ones in Nintendo Switch so it could be a possibility that Valve actually used their hardware during the design process. 

The team who designed and built Steam Deck mentioned in an interview that they will be continuing the iteration on the hardware as Steam Deck progresses in upcoming years. The development process might bring us very surprising changes.