I don't think it's better or worse. Restrictive hardware targets are a perfectly valid game jam. I am amazed to see NES game jams, Gameboy jams, Playdate, etc.
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.
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.