Why is it a waste of time to actually try? If you believe there is no pope, then it is still a reason for you to do this, because it's what Our Lady wants. She wont fault you. And as I said, sedes can pray for this. If the seat is empty, as you claim, then perhaps the consecration brings an end to that? Either way. everyone wins.
When it comes to praying for the consecration to be done we are of the same mind on this. When it comes to practical action to achieving this, there will be differences of opinion.
I have no intention of petitioning Francis to do anything, or to ask others to do so. I am not saying for you not do to this, as you operate under a different set of assumptions, and perhaps your actions may get Mr. Putin, one of the most powerful men in the world to at least hear or think about Fatima.
When Bishop Fellay organized a Rosary drive throughout the world for the consecration of Russia, I was on board with that, and prayed it with Catholics around the world. I have no doubt that Fellay, like you, think that this will come about through these usurpers, but that was not the stated intent of the prayer, it was that Our Lady's request for the consecration would be done, without mentioning the antipope.