"Not recommended to use this with challenges that require significant user experience challenges, for example entering a password on a TV screen with an on-screen keyboard."
Security consideration around the differences between exposure of credentials on a TV screen in a room vs the risk of a cross-device flow
We don't want to discourage the possibility of using this flow with a passkey on a TV remote control
"If you're on a limited input device, and the authentication method the user must pass requires significant user interaction, e.g. entering a password, then you shouldn't use this method; use the device flow instead."
First item to add is guidance on limited input devices.