I'm happy to announce that the game just received "Verified" compatibility status!
You might have noticed it went from "Unsupported" to "Playable" a while ago and I kept fixing things and after a few review rounds with Valve we're finally here!
It wasn't easy because the game was not designed with controller in mind so I had to get creative like virtual cursor and burger-making minigame controls. I think the experience on the Steam Deck is pretty good and relatively intuitive.
The game utilizes a full 16:10 aspect ratio for most of the time, but sex scenes are locked to 16:9 with black bars at the top and bottom of the screen.
PS: In theory, it should also play well on other handheld console devices running on Windows or Linux operating systems.
About using PlayStation controller
To see PlayStation-style icons when using a PS controller, you should disable Steam Input.
Go to the settings [cog icon to the right], then "Properties...", go to "Controller", and in "Override for Slave Harem" select "Disable Steam Input". You can switch between controllers at any time - the game engine will handle the display of glyphs upon pressing a button.
Steam Deck unit provided courtesy of Valve for testing and development.