and like someone pointed out, he could have pardoned in advance all January 6 demonstrators

Ahh yes, back when pretty much everyone on the right was saying, "it wasn't much of a riot, but anyone who broke laws should be prosecuted," Trump should have just come out with a blanket pardon. That would have looked totally reasonable.

Trump also definitely should have had the foresight to know that the establishment hacks actually are insane enough to go after grandmothers that wandered through the capitol building, and found a way to protect them from a bunch of insane establishment hacks that definitely would have respected his pre-pardons.

You've got to be delusional to believe this nonsense. Even from a legal standpoint, it's really not clear that he could have just blanket pardoned everybody. And at the time nobody understood just how truly corrupt and insecure these establishment hacks are, and nobody outside the most paranoid would have predicted that they'd go after journalists who were just standing outside filming or non-violent people who were clearly encouraged by security to enter the building.