Kuo projects that Apple is going to sell 2.5M to 3.5M units of the first gen headset in 2023, manufactured by Pegatron.
This first gen headset will get the software development going. It won't be, by any means, an impulse-buy present like those cheap VR headsets, it will be an advanced niche device, very pricey, mostly a dev kit initially. Dramatically more powerful and advanced. Can't really be compared to those other headsets.
Then in 2024 Apple is supposed to sell 8M to 10M headsets (that includes fist gen and second gen). The second gen model will be lighter and manufactured by Luxshare-ICT.