Each half-bridge is rated for 1A continuous output current. For a bipolar stepper motor, that is the per-winding current; for a brushed-DC motor, it is the per-channel current.
PWM interface and half-bridge configuration
The DRV8428EPWPR accepts PWM signals directly on its control inputs, making it straightforward to drive from an MCU's timer outputs or a dedicated PWM generator. The two half-bridges can be configured independently: use both for a bipolar stepper (full-, half-, or microstep drive) or each as a separate brushed-DC H-bridge. There is no built-in step sequencer, so the host controller manages the commutation sequence. This keeps the BOM simple but places the timing burden on the MCU firmware.
The 16-HTSSOP package with exposed pad is a standard TI footprint, so second-sourcing or a pin-compatible alternate is straightforward if needed later.