The mirror controlling is typically done in such way that one larger stepper motor controls the rotation. The smaller one which controls the beam Y direction is mounted on the shaft of the rotation stepper motor. This is the most commonly used construction.
Some cheap lights can use only one rotating motor for mirror.
Their performance and use is much more limited. PWM can be used to control the rotation speed of DC motor. Mirrors mounted on speakers can be used to laser controlling. They are not as good as real galvanometers, but are much cheaper. Connect the output of the cirucit to a relay.