Sorry I said “we know”. This is possible hear say about what he signed. I was and had been under the impression that what he signed had to do with voiding a election if foreign collusion was found to be true. I remember laughing he signed that back in 2017 and they impeach him over Russian collusion. But I do believe what he signed had to do with foreign collusion.
If the Maricopa County audit proves that Trump really won the county and the state, would the Arizona legislature decertify the results of the election? As the Arizona House refused to tighten the state's voting laws, due to RINO defections, it is questionable whether the legislature would decertify. Then there are the other disputed states, where the audits are not as far advanced.
Finally, how likely would Congress be to overturn the certification on January 6th? I doubt you would get any Democrats to defect, and the usual suspects in the GOP-e would not decertify.