I think what a LOT of pundits are missing here is that the Quest 3 is being targetted at middle income consumers. It's $500-$600 with no accessories needed to function - open the box and go. It's compatible with Android and Windows and can be used both untethered as well as in Rift mode over QuestLink to a PC for heavier performance games.
In other words, a headset anyone and everyone can use for a wide variety of use cases.
The Apple "Reality" headset is expected to come in around $3000 - about the price of a HoloLens - and is tightly tied to Apple hardware, so you need an iPhone and probably a Mac to use it in an equivalent Rift mode. At that price it bloody well had better come with higher specced hardware. World wide, iPhones are about 20% of the market and Macs are around 15%, so the actual market for the Apple headset is inherently smaller (although some countries like the US, UK and Japan are heavy into Apple products, so more likely a success in those regions if all it needs is an iPhone).
The far more likely scenario is that it will be a success within its own market as Apple faithful tend to buy Apple products rather indiscriminately while the Quest 3 will dominate the rest of the market. Remember, the Quest doesn't support macOS NOW, so it's already not a player in that submarket, although it dose support iOS (to a degree).