I'm fairly sure this is either untrue or unknowable. If the official "Harris campaign" spent more than the "Trump campaign" that doesn't actually mean much, considering how many other avenues exist to spend money that escape public scrutiny.
Even if you could account for all the dark money, that still leaves you with leveraging soft power - e.g. Musk using X as a de facto propaganda arm of the Republican party, which doesn't show up on any books.
I'm pretty sure it is knowable. The democrats spent far more.
Musk and X propaganda helped. Also Rogan and other podcasters, but look at how much propaganda the democrat side has/had. All the major media outlets. Reddit, etc etc. Plus the power of the federal government in censorship, courts and the like.
Look, I don't really care and don't trust anyone running for office much. I'm just pointing out what a winning platform would look like. MAGA won because they were speaking to things that more people found important. When the Democrats figure this out, they will be in the winning seat again. If they don't, then they will not win.
Even if you could account for all the dark money, that still leaves you with leveraging soft power - e.g. Musk using X as a de facto propaganda arm of the Republican party, which doesn't show up on any books.