[nom]

You literally just hook a device up to pin 15/16 on an HDMI port.

https://mitxela.com/projects/ddc-oled

DDC is how your OS reads the list of supported resolutions from your display and is present on VGA ports as well. It's just a low speed i2c bus and can be used for other things :)

[tarasglek]

That's so cool. I just recently saw a more recent impl of this: copying fb over spi on rpi. This approach is much more clever and equally useless