I'm in the same boat. I just cannot get them to work; they work sometimes on some browsers, but a solid majority of the time I click on "use passkey" I get a generic error message and end up going back and using the password flow.

I haven't invested more time in this because if it's so unusable for me as an engineer, it's a non-starter for the general public.

And then there is Sony Playstation network. Set a passkey on your account when you’re on a computer browsing their store or managing your account.

Go to the playstation. Can’t login anymore. Passkey not supported.