From what I've seen, PUFs tend to go for a level of security more like "unclonable except by a nation-state with physical access, a battalion of electron micros

From what I've seen, PUFs tend to go for a level of security more like "unclonable except by a nation-state with physical access, a battalion of electron microscopes, and the willingness to expend person-years of effort". For example with a flip-flop PUF I think you'd need to reverse engineer miniscule imperfections in every single transistor.