How many stepper motors can a 32 microcontroller control?

If these stepper motors operate synchronously, theoretically they can control infinitely many.
I used a 32 microcontroller to control a stepper motor while doing a project a while ago. I need to control 10 stepper motors simultaneously, and these 10 stepper motors are independent of each other.
I am using the STM32F407ZGT6 microcontroller, which uses the TB6600 driver. The microcontroller needs to output three signals to the driver: pulse, direction, and enable. The direction signal and enable signal can be generated using ordinary GPIO, while the pulse signal is generated using a timer, which utilizes the output comparison function of the timer. The advanced timer and universal timer have a total of 40 output comparison channels, so the microcontroller I am using can control 40 stepper motors separately.
If you are using another board and also want to control it in this way, you can take a look at the timer resources, how many timers there are, and how many output comparison channels each timer has.

This depends on the peripheral resources and has nothing to do with the number of bits in the microcontroller.