I’ve had a steam deck for a few months, and have tried dozens of games already. Both pirated and owned on steam.
If it’s a pirated game or a game that’s not available on steam, I just add the .exe as a non steam game and launch it with the latest GE-Proton version that I’ve installed with ProtonUpqt. It literally always works flawlessly.
Lutris is much more complicated than this, I know cause I’ve used it on desktop linux in the past.
So why is Lutris so recommended to people here, especially to beginners?
Your way doesn’t always work for me, been a few games I wasn’t able to find a workaround for without Lutris. Shredders Revenge being one, Dying Light the other. Lutris Just works. Install the game running the .exe in Lutris, then once installed, change the .exe path.