There have been any number of Maxwell's demon claims, they all fail because 2LOT is fundamental
Umm, which Maxwell's demon claim actually failed? Many of them were presented in peer-reviewed journals and subsequently confirmed. They just generated too little energy for being exploitable practically. But they were also demonstrated only with tiny isolated systems - army of Maxwell's demons working in unison would release way more energy - and this is just the way, in which macroscopic overunity devices IMO work.
The many similar systems indeed exist, because (1) and (2) together give you a lot of candidates. Just as there are a lot of machines that look like PM, but in fact are not.
They also share many similar aspects, for example low-dimensionality of particle motion and energy concentration gradients which I talked above. For example Thibado talks about possibility of draining of graphene buckling energy with piezoelectric material whereas Steorn, QuantaMagnetic and QGEnergy already independently presented mixtures of graphene with piezoelectric material as a source of environmental energy. It can still be a damned coincidence - but I don't believe in coincidences.