First time programming still needs a hardware connection to be made between P1.5 and GND, but after that holding the 1st key while connecting USB lands you in the bootloader!
U8X8_GP1287AI_256X50_4W_SW_SPI u8x8(/* clock=*/ 0, /* data=*/ 2, /* cs=*/ 14, /* dc=*/ 4, /* reset=*/16);