Not directly. Only Duet3 hardware supports direct drive of dotstar or neopixel.

With Duet 2, you'd have to drive a pin that switched a controller that, in turn, drove the LEDs.

Duet 3 uses CAN-FD bus to communicate between the main board and expansion boards, and we plan to make a Smart Tool board using the same CAN-FD-bus.

For devices that are just sensors, CAN is likely to be overkill. Duet 3 uses a simpler interface with a 4-pin connector to connect sensors, including endstops sensors, Z probes and filament monitors. The benefit of CAN-FD is that it can handle high data rates and it can tolerate the ground noise that stepper motors and PWM'd heaters cause.