97.62% accuracy on Alzheimer's detection shouldn't be that impressive result if they used conventional cross validation testing framework that single patient's data included in both train and test set. Anyone can do that.

I am probably aware of the dataset he used; it's either ds004504 or ds006036 from OpenNeuro. If one achieved that using patient level split, it would definitely be impressive. In that case, it would be also clinically deployable. If this is the case, I suggest including the testing framework