It’s even better, it’s totally unrelated and non-restricted to running on a singular piece of hardware. A “Steam Deck game jam” would be a Linux game jam. Leave the proprietary hardware out of it.
A Steam Deck game jam would not be simply a Linux game jam. The form factor and capabilities of the device could have creative uses. The device includes unusual rear buttons (R4, R5, L4, L5), touch-sensitive joysticks, dual trackpads which are also clickable, etc. -- it's not really fair to say that targetting a game for this piece of hardware is simply targetting Linux, just because the device runs Linux.
The steam deck has some unique features. And regardless, it's just about sparking creativity. But I am curious if anyone has gotten Aperture Desk Job (Steam Deck exclusive) to run on another device.