We demonstrate here efficient teleoperation by both valid and arm-amputated participants on Reachy2, an opensource humanoid robot made by Pollen Robotics that ranked 2nd at ANA Avatar XPRIZE. The 3D parallel joint Orbita included at neck and wrist levels enables reproducing natural head and arm movements. This translates into an accurate egocentric view, and provides the opportunity to test a novel prosthesis control based on natural arm movement reconstructed by an Artificial Neural Network (ANN) that receives movement goal and stump motion as inputs. Direct first-person teleoperation by able-bodied participants (n=14) elicited a 100% success rate for grasping objects at various locations, with best possible usability scores and small workload scores. High success rates (>92%) were also obtained when all distal joints from the elbow onward were operated with the novel prosthesis control, using a movement goal identified through gaze-guided computer vision. While usability and workload scores were slightly degraded when able-bodied participants used the prosthesis control as compared to direct teleoperation, both were scored similarly well by a sample from our target population (n=8 participants with transhumeral limb loss). This platform and control schemes offer broad perspectives for prosthesis control, but also for teleoperation robotics and human-robot interactions.