Just playing devil's advocate here, but what if it's something like: an omnidirectional thrust vector https://link.springer.com/chapter/10.1007/978-981-10-2875

Just playing devil's advocate here, but what if it's something like: an omnidirectional thrust vector https://link.springer.com/chapter/10.1007/978-981-10-2875-5_24 https://link.springer.com/chapter/10.1007/978-981-10-2875-5_... but using a nuclear powered jet engine? (Like the Burevestnik linked above) Sounds crazy, but if it were done, and if it were a drone that is 90% engine and fuel (no pilot, no life support), I could imagine getting something that performs similarly to what we have seen in these videos. If we add on top of being 90% engine and fuel, even a slight improvement in engine performance, or a willingness to let the engine destroy itself after each use, it would have better performance than human-containing sustainable-flying aircraft.