Thanks to the EmuDeck program, it is possible to play PS2 games on your Steam Deck. Here's what is required in order to do so.

Again, like PCSX2, you can set up Dolphin to run games at higher resolutions than you’ll find on their actual consoles. ImgBurn can again be used to rip your Wii ISOs.

PS2 emulator PCSX2 adds Vulkan support PCSX2 now supports Vulkan, and it "should make a couple of harder to run games much easier to play" ...