fbcp allows you to copy the framebuffer of the main display to the LCD, however I don’t think you could get video on it. I think you’ll get about 20fps at the most on one of these screens via SPI.
The Raspberry Pi forums have some background on this. As long as you can get the display to show some output already, it seems like you just need to use fbcp and set that up to run on boot. Kodi is a GLES application, so I am not sure if that will work as expected however. It already seems that the FB is duplicated if you can get the splash screen up.
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