Simple logic shows that to be wrong.
In fact we do know who would have won such a hypothetical perfect election. It would be the same person who this past election...Joe Biden.
Unless there existed actual proof that there were not just incidents of fraud just as there's always been cheating and attempts at cheating in all our past elections...in order for Trump voter’s false claim to be true, one would need proof of sufficient fraud, enough to have changed the election results,
It has already been proven that there was not sufficient fraud to change the election result.
Therefor Joe Biden would have won such a hypothetical election just as Joe Biden won our real world actual election.
Trump voters can dishonestly try to sow doubt in the minds of the voters by continuing to repeat their lie but they can’t change the truth. Repeating a lie won’t make it true.
Joe Biden legitimately won the election fair and square. False stories that he didn't, will go down in history as what we all know them to be, simply part of..."THE BIG LIE".