Because the zero has the Linux OS, it is not suited for real-time GPIO operations like driving unipolar stepper motors. One solution is driver based on the i2c to PWM chip which drives MOSFET H-bridge drivers.
There is a HAT for pi that supports this way of driving steppers, and it has a python library.
https://www.adafruit.com/product/2348
This supports 5 wire unipolar steppers!
Because the zero has the Linux OS, it is not suited for real-time GPIO operations like driving unipolar stepper motors. One solution is driver based on the i2c to PWM chip which drives MOSFET H-bridge drivers. There is a HAT for pi that supports this way of driving steppers, and it has a python library. https://www.adafruit.com/product/2348 This supports 5 wire unipolar steppers!