[roblabla]

What prevents you from using Unreal Engine? It has AR, and it seems fairly mature, though I've never tried it. Is it technical limitation/pricing?

[peteforde]

Apple won't even release an Unreal SDK for Vision Pro, since they are still fighting over Fortnite.

Unity has a major lock on the VR/AR/MR space.

[jhaehl]

Apple's Vision Pro support as well as Niantic's Lightship ARDK are currently only available via Unity. In general, many of the tools for new AR platforms and devices are developed for Unity first. With all of this backlash that might change in the future, but for the time being the overwhelming majority of AR support goes into Unity.