The network connection to the Steam servers was not working, so I ended up following the advice of oopsidaysy on Reddit of enabling developer mode and disable Wifi power saving in the developer mode options. It seems to work now, although the battery might drain quicker.
Of course, this super simple game plays well on the Deck.
Screenshots marked with 🍒 are created by syltefar and are considered public domain, free to use for anything. If you want to, you can note where you found it and link to this page.