WhatsApp does it the other way (scan a QR code on your desktop with your phone to log in to the desktop side), but we certainly could have a similar system in Riot. A QR code on desktop would automatically log you in to your phone. @uhoreg says emoji verification might be useful here.
https://github.com/matrix-org/matrix-doc/pull/1544 might also be useful
Discord's new scan QR to login feature is an INSANELY GREAT experience. If we could do one QR for logging in and setting up cross signing that would be amazing.
Discord's new scan QR to login feature is an INSANELY GREAT experience. If we could do one QR for logging in and setting up cross signing that would be amazing.
A downside of making it really easy to login:

Discord's new scan QR to login feature is an INSANELY GREAT experience. If we could do one QR for logging in and setting up cross signing that would be amazing.
A downside of making it really easy to login:
I think with a warning (including confirm) in the "origin" app, this is not a big deal
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Discord's new scan QR to login feature is an INSANELY GREAT experience. If we could do one QR for logging in and setting up cross signing that would be amazing.