Would I be able to develop a game using either AR, VR, or WebXR? I read you article on Game Jam submissions, but there was no mention of XR under platforms. To keep it simple, I was thinking either Mobile AR (App Store or WebXR),  or VR (Itch has the ability to host VR games or WebXR could be an easy lightweight solution).

Would the judges have access to platforms that could run AR/VR? Definitely not asking the judges to buy new equipment for the jam - but I might not want to submit a game that can’t be judged.

There's no judges, your game will be judged by the public. Which means that releasing a game for VR will limit the number of people that'll be able to play and judge your game.

Gotcha, thanks!