This is a screenless computer, meant to be used with XR/AR glasses or an external display. The Steam Deck motherboard goes in a 3d printed housing underneath the keyboard, giving you a keyboard that only needs to be connected to a display for a portable computer set up.
Here’s the hacker news discussion on it, includes comments from the creator of the project
Can still pull off the “no computer” look with just a steam deck in a backpack. It’s kind of cool(?), but definitely a lot of effort going into “un-gaming” a steam deck. A framework mainboard may be a better option for this tbh.