Based on the "Build immersive web experiences with WebXR"-Video for visionOS there is no way to disable the consent prompts for entering an immersive experience or consent hand-tracking. For the microphone it's possible to "greenlight" specific websites for mic input, which works great.
I'd welcome it, if it were possible to add specific websites in the settings, in which those consent dialogs aren't shown each time. In my opinion, the user interaction through a button that launches the experience would be sufficient to not disorient.