I have been trying to determine the validity of vote fraud claims. (This is separate from Pennsylvania not following their own voting laws regardless of being upheld by the courts.)
The following is typical of the fact-checking I find in the press. I see the same fact-checks in other publications. The only problem is that the vast majority of them are strong left-leaning. If you read enough of these then you get the strong sense that most of the vote fraud claims can be explained away.
I consider it well within the realm of possibility that a few leftist people in a few counties that matter enough to sway the election would cheat. I think that the political left is highly corrupt. However, I am not saying that this is what happened. I can't prove it.