The Mike Johnson secret that Trump referred to at his Nazi rally might be this.

[WestMichRad]

84. Y'all are too hung up on technicalities.

I think their “secret” is much simpler: TSF declares that the election was rife with fraud (offering no specific information to prove it), therefore the electoral votes are null and void and the House has the power to decide the outcome. Since the election was fraudulent, nothing can be trusted and it is the division of power that existed on Dec 31 (or Jan 1, or pick a date), when a majority of states are/were controlled by Republican majorities, and thus they will win the 50 vote selection in the House. Then he just needs one SCOTUS justice to swear him in and he declares the constitution to be null and void (including the power of SCOTUS to overturn the scheme).
Far fetched? Maybe. Trumpian fever dream? Definitely.
As Lawrence O’Donnell pointed out, the problem with any scheme, this time around, is that he isn’t currently the president, so he lacks the power to do this. Full stop.

But it would not stop he and Johnson from trying.