One degree of freedom carrying forearm mass plus payload. Do not assume it can be a size down from the shoulder: on Unitree's H1-2 and G1 the elbow and shoulder are specified at the same torque as each other. Weight matters more here than the torque figure suggests, because the elbow actuator's own mass becomes a load the shoulder has to hold at full extension — every 100 g spent here is paid for again upstream.