Technically, the 12th Amendment says:> "The President of the Senate shall, in the presence of the Senate and House of Representatives, open all the certificates and the votes shall then be counted;"
Also, the Electoral Count Act states: > "Two tellers shall be previously appointed on the part of the Senate and two on the part of the House of Representatives, to whom shall be handed, as they are opened by the President of the Senate, all the certificates and papers purporting to be certificates of the electoral votes, which certificates and papers shall be opened, presented, and acted upon in the alphabetical order of the States, beginning with the letter A;"
So in theory, based on both the Constitution and Federal Law, Pence can open anything that claims to be Electoral College votes, and can decide which votes to open. He's the presiding officer over the whole proceeding. Pence then counts the votes as he deems fit, announces his count, and then calls for objections. So IN THEORY, he could decide to open the alternate electors' (the ones who voted for Trump in defiance of the "official" voters) votes, or open/count any of the votes from the disputed states, or open both sets. I don't know what would happen if he opened both, but if he opened none of the Electoral College votes from NV, AZ, PA, MI, WI, and GA, then neither candidate gets 270 votes and there's a contingent election. If he opens up the Trump electors' votes only, then objections can be raised by the House and Senate. If Democrats only run the House while the GOP holds the Senate, assuming a party line vote, then the chambers disagree and the votes are counted. If Democrats control both chambers or if both chambers both voted to object and discard the Trump electors, then still no one gets to 270 and you get a contingent election.