I think most test of bell inequality are made using photons. I'm not sure about this inequality. Neutrons are much bigger than photons [1], but somewhat similar experiments of interference have been made with helium atoms and even small molecules (with 10 atoms or so).

So if they say it's big in the quantum word, I expect at least a molecule. And the article saying macroscopic everywhere really sugest basketballs.

From the initial description, I was optimistic and I was expecting small dots of "dust", or a tiny thin membrane. There are some experimental results with extremly small object, but I guess they have a lot of thechnical problems and are difficult to use them in complex measurements.

[1] Ignoring a lot of technical details.

Neutrino ≠ neutron. The “ino” in neutrino is like a diminutive. Neutrons are much heavier than a neutrino.

I don’t think they have a positive lower bound on the size of the smallest mass eigenstate of neutrinos (though they do on the other two).