I'm not sure it's fair to say that Facebook had a 7-8 yr head start because Apple has been developing every single component that goes into the VR headset for well over 10 yrs. They design their own cameras, displays, micro processors, lenses, speakers, sensors, etc. Apple has hundreds of engineers working on each of these components for various devices they sell. They've shipped a billion+ of their own custom processors and have a world class chip design team to make custom chips for specific products. Meta has no where near the level of hardware design expertise that Apple has. They've also been slowly laying a lot of this ground work for years now with ARKit and LiDAR on iPhones / iPad Pro, moving Mac's to Apple Silicon and supporting iPad apps on it (allows them to bootstrap the Vision Pro app store).

Even if Apple found the displays, cameras, sensors, etc. the one thing they won't find available is the processors(s). Apple is shipping an M2 chip, which they use for desktop computing as well as a custom new chip to handle sensor information. I read that the actual parts cost of the Vision Pro is $1500, and that's with Apple having huge contracts with their suppliers for other components and getting a discount. Add in R&D costs and even at $3500 Apple is likely not making much on this device. If Meta were to make a similar device I think it would cost $5k or they would have to sell it at a major loss.