That's news to me https://developer.mozilla.org/en-US/docs/Web/API/Web_Bluetoo...

Websites cannot use Bluetooth anywhere. The QR codes shown in the blog post are not passkey QR codes, which is likely what's confusing you.

Interestingly, only on desktop/Android and not iOS it seems.

Chrome on iOS uses WebKit, so that makes sense.

(*I think in the EU, iOS Chrome can use Blink, but I am not sure if it actually does.)