Use an SSD1306 OLED display as a secondary monitor by piping video to it over the DDC bus. This is a total hack and by far the worst way to get a second monitor.
This demo will only work on Linux using X11, and requires the i2c-dev kernel module loaded.
Update: Command line options for dither and brightness have been added, and the script now only updates the parts of the display which have changed.
I've added a wrapper script which handles the xrandr framebuffer setup and teardown, and attempts to determine the i2c device number based on its name as output by i2cdetect -l (or cat /sys/class/i2c-dev/*/device/name). In my case, that's i915 gmbus dpb. The script assumes the primary display is named eDP-1 and has a resolution of 1920x1080. You should definitely read through/modify the script before running it.
More info: https://mitxela.com/projects/ddc-oled
PyXCursor from here: https://github.com/zorvios/PyXCursor (modified to also return xhot and yhot)