GPIO on robotic cape

Hi, on BB blue there were gpio sockets, they do not exists on the robotic cape. The cape is not also “thru”, i.e. no sockets for another cape. How can I use GPIO when the robotic cape is plugged? There is a socket SPI1.1 with pins SPI11_MOSI, SPI11_MISO, SPI11_SCK, SPI11_SS1, can there be reutilised as GPIO? If yes, how to translate their names to values for gpio_export etc.?

Guessing from this,
gpio1[17], gpio3[17] are free. Is it also the case for gpio3[21] if IMU is
not used? I need 3 x GPIO.