Just popping here to share some great news - cpd is playable on Steam deck! Although the game is not officially supported on the device, and thus, may not present the optimal playing experience, a community member discovered a way to make it work.
The solution, as our discord member rattlesnakejones shared, is to in the Steam deck, before loading, click the gear tab for settings. Go to compatibility and make sure that “force the use of a specific steam play compatibility tool” is checked. Then enable proton experimental mode. And that's it. With these few simple steps you should be able to experience the game in Steam deck now. We hope you enjoy!