Hello @alpaka
unfortunately GPIO36 (one of the GPIOs used for Port B) is an input only GPIO. See here - section M5GO Base Pins and here - GPI: GPIO34-39 can only be set as input mode and do not have software-enabled pullup or pulldown functions.
I2C however requires one GPIO as output (SCL) and one GPIO which can be an out- or input (SDA). Therefore Port B cannot be used for I2C.
Thanks
Felix