It should probably be a plugin of some sort rather than built in the engine. It's a very small use case scenario and the devices are expensive and rare.

Like the comments said there are also concerns about maintaining it in the long term.

Having made games in Godot, I'm quite excited by the prospect of making the games within vision OS and playing them in a virtual 3D space. But Apple has only shown its vision for it and the future prospects are very uncertain due to the economic climate and affordability.