In the context of innocent until proven guilty, I mean.
Without a conviction, what would there be to pardon her for?
CMD
A blanket pardon "for all acts from the moment of her conception until (insert date of pardon)" would be constitutional.
Edited to add: I fully expect Emperor Three Putt to issue a stack of them on his last day, for Felonia von Cankles, Her Sweet Huma, Cheryl Mills, and on down the line for every one who has the goods on him.