What kind of raw signals can the device generate? Can it measure gravity in various directions? Or is the output just a single scalar?

It's a rack sized multitude of sensors on a boat on the ocean.

It's 'locked' to the tidal surface (meaning an internal tide model and a mean global ocean surface model are onboarded) and perturbed by wave action, the heaving pitch and yaw presaging a decent chunder (it's being trialed on an Australian Navy ship)

Likely single channel gravity signal and three axis inertial measures .. as outlined in this abstract:

Software Ruggedized Atom Interferometry for Strapdown Mobile Quantum Inertial Sensing

  Here, we report world-first demonstrations of a dual quantum gravimeter operating in a relevant maritime environment, with an unattended uptime of >144 hours, ...

  In addition, we present a compact 3-axis quantum inertial sensor capable of high repetition rate operation in extremely harsh environments.