Not the developer, but the description literally says that the game is "made for the playdate", which is a small handheld console.
You can read more about the console on it's website here: play.date
It's possible. (I have a 3440 x 1440 monitor)
First, create a shortcut for the game, then right-click said shortcut and select properties.
Second, click on the "Target" text box and add the following text:
-screen-fullscreen 0 -screen-height ???? -screen-width ????
(Make sure to change the question marks to the height & width of your choosing.)