I would think there were sufficient procedural irregularities to toss the election in PA based on the precedent of Bush v. Gore. The state Supreme Court and executive ignored the clear legal requirements stipulated by the state legislature. Why the panel threw out Giuliani's lawsuit is unclear, unless he screwed the pooch on the legal argument completely, which is unlikely. I would guess the three judge panel is simply punting, but doing so quickly, knowing this would wind up before SCOTUS anyway.
The substantive fraud argument is more difficult to prove because it involves facts that have to be established, and have to be established well enough to show conclusively that Trump won. It's doable, but much more involved.
Here too.
https://justthenews.com/politics-policy/elections/amistad-project-filed-election-litigation-michigan