Nancy did definitely set Reagan's scheduling with the advice of an astrologer to the extent that the astrologer decided the exact date of the 1985 Geneva Summit, though Nancy partially admits it was a coping mechanism due to the assassination attempt on him, I don't think it's likely that it influenced the actual decisions being made considering that it was only leaked that the astrologer had an iron-grip on his scheduling to the point where they had to be consulted for Reagan to fly anywhere.
As for tfg, yeah, I mean I can't really say much, dude literally hired his son's girlfriend and shit so fair lmao
Though I also think it's fair to say that at least Biden seems to have educated officials where it matters, one of the pros of electing a guy who sees himself as having to do the actual presidential duties 'by the book' and that it hopefully reminds people of what an administration is supposed to be.
This also might be beside the point, but the snopes article on the matter say that there are definitely signs of Alzheimer's during Reagan's presidency according to one of his children as well as a journalist who seemed to imply he would have these sort of 5 minute "where the fuck am i" moments, but that the doctors checking up on him during presidency insisted after he was diagnosed with Alzheimer's that even with the hindsight 'they never detected any evidence that his forgetfulness was more than just that' and 'there was never anything that would raise a question about his ability to function as President,'
I would say that they probably have had ample opportunity to come clean if they were simply trying to make the it seem like the Reagan years weren't a result of Alzheimer's