My understanding of Pence's pre-January 6th position on certification was that he would be willing to do something if a state court or state legislature decertified or otherwise attempted to change its slate of electors.
But that didn't happen. As of January 6, not a single state legislature had changed its slate of electors, and Trump hadn't won a single case. So, on January 6, Pence stated his belief he had no legal justification to stop certification, and I believe he was correct.
I think a lot of folks got caught up in the hype of "the Kraken", and a bunch of the claims being made by Giuliani and others that just didn't pan out legally. There's a big difference between "I believe the election was stolen", and "I can prove in a court of law that it was stolen". There's also a big difference between "I can prove there was fraud", and "I can prove that there was fraud sufficient to overturn the election." Accusations and assumptions that may seem logical or reasonable aren't going to get you over the evidentiary hump.
I don't think it is either fair or reasonable to have expected Pence to derail the January 6 vote based just on his own belief -- unsupported by court decisions or the actions of state legislatures -- that the election was fraudulent or stolen. And expecting the VP to have a sufficient level of personal knowledge regarding the detailed facts at issue in each of those cases also is unreasonable. He had to rely on the states, and they did not come through.