I would say approx 70% are not documented. Problem I have is that the demo code references command codes in the display initialization that are not documented in the driver datasheet. The site gives sample demo code (download) that is written by the manufacturer of the display 'EastRising' and also links to the GC9A01 driver datasheet here.
I recently purchased the '1.28'' IPS TFT LCD Display 240x240 Round Circle Screen for Smart Watch' here: buydisplay