I would actually say it can't be determined simply because Golden Prime has the hype that would put him on MM level just 0 feats that would confirm it. But sundipping for that long might make it possible considering what a few seconds/minutes usually does for him. Like I said before Golden Prime only has a chance of victory when it's clearly obvious he should win. Say anything of around Superman 1 million or SBP on guardian amp put together would be around where I'd say Golden Prime Stomps. However anything above that just isn't viable to say how he would preform.
void defeated him in his single highest showing to date in an arc that made it clear he was an immortal cosmic entity with unkown/unlimited powers.
anyways, post retcon MM has warped the multiverse, recreated galaxies with a hand gesture and subdued the beyonder. pre retcon molecule man was above the LT, so that's that. what did million ever do that puts him above post retcon MM, let alone pre retcon?
PR Molecule Man wins but otherwise Golden Prime wins. The strongest Superman even have 5D IMP powers so he could probably do almost anything he wanted.
He needed a true reality warper to assist him in bring back lois. Pre-retc mm was near equal to Beyonder, the same being that ended all death by killing death herself. Both mm takes this. Primes solar is turned into kryptonite.