It fulfills a few purposes.
Firstly it's part of the usual late-weekend media blitzkrieg that will have the entire media machine tripping over each other first thing Monday morning to break the story to the general public (winding them up on their own free time when they should be relaxing), the public themselves will be frothing at the mouth over these wackier weekend issues first thing come Monday, and probably stay talking about it all week having missed other, smaller changes and announcements in policy during their working hours through the rest of the week.
Secondly, probably more importantly, it forces the dems and their pocket judges to pick a hill to die on; even if Biden hadn't signed his EO's and pardons and an aide was doing it, how do we handle it going forward? If the dem judges come out to say that what Biden's aide did was legit, then that invites any future administrations to do the same thing. If they say 'no, that's absolutely not allowed' then any future administration can throw that back in their faces the next time they try to pull this bullshit. It's not about repealing any sort of EO's or pardons, it's about putting the dems into a corner and making them pick a position on the matter so that the rules of engagement going forward are plain and clear.