Like Atelier Rorona, game is working fine on Steam Deck. Opening (intro) video works, gamepad input works, audio works.
Only the launcher needs touchscreen input as mouse cursor does not appear before touching screen. In-game menu works with gamepad though.
proton 8.0-1x1 2023-04
Compatibility Report
System Information
I confirm:
steam-936180.log
Symptoms
Showing test pattern when opening video, and the video will be skipped.

Reproduction
Force Proton 8.0-1 to launch