As I was finally able to get my hands on my Q3 Steam Deck, I ran some tests on Move That Box. Turns out I don't really need to change anything and game just works perfect on the Deck with Proton out of the BOX. ːlunar2019coolpigː
Text is visible, there are no problems with music or graphics and you can set buttons for Steam Deck layout in the menu.
Simply. Move That Box! plays awesome on Valve's Steam Deck.
There's a gameplay video: