Valve made a handheld system. While I would have designed it differently, the point is that it is capable of running Cave Confectioner, with some caveats.
Cave Confectioner cannot currently *officially* support the Deck because it cannot be played entirely with a controller. For that to change, an on-screen keyboard needs to implemented. The layout is to be determined.
Much of Cave Confectioner's codebase evolved into RSOD, which is designed to be fully playable with a controller when it launches. Cave Confectioner is still being maintained, and full controller support is still a possibility.