the thing with the moon landing (or spaceflight in general) is that it’s very easy to verify for other countries since many of the satellites send a radio signal all the time and you can actually receive that radio signal from other sides of the world. this way, you know where satellites are (if they want to be discovered). so, we know Yuri Gagarin made it to space because of the radio signal, and the same would likely be true for the moon landings (although i actually hadn’t checked so far).