Any pardon Trump issued, except for himself will be deemed valid by the SCOTUS, unless they paid cash for it and it can be proven. Even if he wrote one in secret a week after he was out of office, they would need to prove it. Nobody will know about it until they whip it out and show it to the judge. Pardon power was intended for presidents, not criminals like Trump and there is little precedent and scant words about it in the constitution. It is a flaw in the system that Trump full exploited, the only brakes on it for him, was they lose their 5th amendment rights and could testify against him after he pardoned them. That is what Rudy will do I figure and why Trump cut him off without a dime months ago and Rudy is flat broke.