Not sure on impedance but rtings.com did a pretty good review of them going over sound signature with graphs/charts if you are into that sorta thing.
As far as the serious specifications goes... that is how Apple has decided to release/market these headphones. I don't think these are anywhere near targeted toward an audiophile who is looking for top-tier listening headphones. These are for Apple ecosystem users who have the money to spend on a premium product that is a step up from AirPods Pro. Now when I say premium I don't mean audio quality vs wired headphones but in their class (ANC, wireless, etc) they are really good. If you compare then against other wireless ANC headphones they will win most fights from sound quality, ANC, ease of use (if you're into the whole Apple ecosystem), swapping between devices seamlessly, etc. Their build quality (aside from the case, yikes) is leagues ahead of another competing ANC wireless headphones as aluminum and stainless steel aren't cheap materials and the machining is top notch.
It's one of those, you're buying it for the whole package and the name kinda gigs. If you're questioning yourself as to "why would I buy it when I can get better stuff" then you probably aren't the target audience for it. I know that sounds weird to say but it's the same reason someone will spend extra on a high-end item like nice shoes, a purse, a watch, etc. They're buying it for the whole package and are willing to spend the extra money. Casio and Rolex both tell the time but the Casio will set you back $20, the Rolex $5,400.
I'm not saying its right or wrong that's just how it is - Apple is a luxury brand and that's how they have placed themselves in the market.