Is there an experiment that shows the entangled particles are NOT set before they are separated? It seems to me that it's fairly easy to explain why one partic

Is there an experiment that shows the entangled particles are NOT set before they are separated? It seems to me that it's fairly easy to explain why one particle correlates to the other. Both of their properties are set before they are separated. We just didn't measure those properties beforehand. I've read and watched a lot of quantum physics on youtube. This kind of refusal is always elusive, as in nobody has an experiment to negate this explanation (or maybe I miss it). Wave-particle duality is another one that doesn't feel real, especially when we fire one electron and we say "electron interfere with itself". It seems we think of it as a wave simply because the electron is too small for us to see. And that's it. Somehow we come up with this convoluted explanation with catchy name "wave-particle duality". This one is also elusive. Is there an experiment that refuses this explanation of how wave-particle duality isn't real?