By "stealing" I mean if he loses Pennsylvania but somehow turns it into a win through a bunch of bullshit lawsuits.
Trump's problem if he is trying to create a legal steal of PA's electorate votes is that the State government is entirely controlled by Democrats and the State Supreme Court has a liberal majority. The legal bullshit he tried to pull in Georgia in 2020 when he called Raffensperger to get him to "find" more votes won't work here. While the Secretary of State, Al Schmidt, is a Republican. He famously refused to go along with Trump in 2020, and testified before the January 6th commission, which is why Josh Shapiro (PA"s democratic governor) appointed him.
So I just don't think there is much Trump can do to overturn a loss here. At least not on the state level. The federal courts might be a different story, however. But the Third Circuit Court of Appeals (which covers PA) is not a particularly rightwing court. Of the 13 Judges on the Court who are fully active (not on "senior status"), there is a bare Republican appointment majority (7 were appointed by Bush or Trump vs. 6 by Obama or Biden), but there is also a vacancy, which probably won't get filled in time because of a bullshit racist smear against Biden's nominee. Still, the Bush appointees did not put up with Trump's bullshit in 2020, so I doubt they will now. On the other hand, Sam Alito is the Supreme Court Justice who is in charge of the Circuit.
Still, compared with other swing states where the government is more divided, I'm more confident that the people in charge of Pennsylvania will not be receptive to overturning a Harris win here.