Seriously, just tried passkey on an Android phone of mine with a burner account. I would not recommend this to anyone. Passkey as a tech might not be the issue, but the lacking option of just removing devices and passkeys freely from your account is just not acceptable. The vendor simply has different ideas about security than I have and it is not just restricted to serving me "safer" ads.
The solution is to set up multiple pieces of secure hardware, not writing down the keys to the castle on a piece of paper.
It is true that you do need to be rich enough to own a phone and ~100 USD of something else (laptop or USB), which does put redundancy out of the reach of a large portion of the world. But then they can just use regular 2fa at the expense of not being phishing-proof.
Things being this complicated makes them a non-starter. A nerd vanity project.
And this isn’t a knock on the “intelligence” of the general population. They quite rightfully won’t want to spend their limited time on God’s earth learning about all this.
But information sovereignty is crucial when it comes to this stuff; losing that is a regression that will cause problems