Help: MR Passthrough shader

hello. i am trying to make a shader that affects the whole passthrough camera using unity for the meta quest 3. so far i've seen examples that apply shader materials to planes (as found here: https://github.com/xrdevrob/QuestCameraKit). and i saw one single example using the whole camera view (here: https://x.com/BastionReality/status/1912358908804333844). there's no information i could find on how to achieve the full camera shader. so if anyone has any guesses on how to achieve it please help a guy out