> What happens when I go to the same site on a different platform?

You click the "log in with QR code" button, scan the QR code, and authenticate using your phone.

Unfortunately that only works from phone (and watch) to computer. If you don't have the passkey available, you click "forgot password" and set a new one, same as with a password.

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pigeons 39 minutes ago | parent [-]

That's part of the horrible experience I hate. why should I have to have my phone to login on my computer.

	▲	jeroenhd 25 minutes ago \| parent [-]
		You only do it if you want to. You can put your passkey in keepassxc or 1password or bitwarden or google's password vault or any other cross-platform passkey platform. It's only a problem if you pick a platform that locks you out, even then there's workarounds. It's not a replacement for logging in every day, it's more a replacement for typing over the 64 character random password from your phone's password manager on the library computer.