This is good in theory but in practice doesn't always work.
It isn't
just a QR code like I would like it to be, its a QR code
and you need bluetooth. Maybe there is a hypothetical world where bluetooth drivers actually work on windows machines and can connect to a mobile device seamlessly but that is
not my experience. Across multiple windows machines i often have a problem where windows just decides the machine doesn't have bluetooth, and will
refuse to display the QR code without any explanation. It doesn't tell you that bluetooth is the problem it just says "insert a hardware token to authenticate".
I would love for this feature to actually work but every time I've needed it to it hasn't. Literally this week I only had a passkey on my phone, but at the time I was in Linux with Firefox, and afaict the qr code workflow basically requires either chrome or windows 10.