I suspect that what they're offering is not only feasible but achievable with modern technology. The glut of cheap sensors and research into dynamic, multi-axis control thanks to drones makes it easier for something like this to come into being. However, I am skeptical about their ability to build something that can fly for a long distance due to the low energy density of current technology. Even with a gas powered turbine system, their efficiency is capped at around 30%? Theoretically, heat recovery can boost that to 85%, but that equipment is heavy and it's complicated to mount https://www.wbdg.org/resources/microturbines . I don't know the answer to this question but I do hope that they find out!

Good luck guys! You're solving some really Hard problems here.