The latest Steam Deck OS 3.4.6 Beta driver features a surprising addition, with Valve noting, "Ray-Tracing is now available in DOOM Eternal."

This is surprising for several reasons, with most of them being a variation of the fact that the Steam Deck is a handheld and designed to deliver optimized performance for modern games played at a lower resolution instead of running everything with Ultra settings enabled like it's a GeForce RTX 4080.
Support for DOOM Eternal's real-time ray-tracing for reflections is the first time Steam Deck users can enable the hardware-intensive but visually impressive effect on the handheld - thanks to id Software's implementation being via the Linux-friendly Vulkan API.
Even so, Valve engineer Pierre-Loup Griffais took to Twitter to confirm that DirectX RT or DXR support is "also in the pipe, just not quite ready yet" - the version we see in most games with ray-tracing support.
Ray-tracing on the Steam Deck sounds excellent on paper, and many GPUs can run games like DOOM Eternal with ray-tracing enabled, but it's another thing to do so with a playable frame rate. In the case of DOOM Eternal with RT on the Steam Deck, the publication Rock Paper Shotgun fired up the game using the 1280x800 resolution, Medium quality visuals, with ray-tracing enabled. And with that, playing what looks like the game's opening sections, the frame rate sat between 30-45fps without any upscaling or dynamic resolution enabled.
Of course, in the world of playing fast-paced shooters on PC, it's usually 60fps or nothing - so you might not consider 30fps "playable."