If someone is reading this and is interested, I've used a tool (can share it at request) on my windows machine steam installed game. Then I've used the local network game download to install it on the steam deck and then I connected to my steam deck with ftp and force overwrote all installed game files on the deck's side. Then you need to add a startup argument to the game in steam and you're golden.
Also when Roman comes to pick you up, you will hear Schweine and Zit! is also working

fusion fix and song restoration fully working on steam deck