No, Pelosi is not President unless Trump or Biden fail to be sworn in. She would be a temporary President but a dangerous one. It won’t get that far.
Possibly a 12th Amendment process will proceed but a nasty court battle will take place in parallel or before. Trump wins under a 12th Amendment process, expect Democrats and Establishment to fight tooth and nail to stop any 12th Amendment proceeding even though it’s mandated by the Constitution.
This lawsuit will go nowhere with this derelict Supreme Court but as long as Pence is being sued, he can either step down or go along with Biden Electors or postpone the count of Electors until the matter is resolved.
The lawsuit appears to be designed to buy time.
As the Supreme Court has been deliberately sitting on emergency petitions, allowing the Democrats and Establishment to run out the clock, the Court will show its true colors if it moves this Amistad lawsuit up ahead of others in order to deny it standing.
My money will be on supremes postponing all such cases past Jan 20, 2021.