I am simply suggesting that the dems really wanted something to 'stick' to Trump to stop him from being president again, whereas I doubt anyone was going around looking for things VP Biden did wrong at the time with the same enthusiasm.

This isn't the dems. This is between the National Archives and Records Administration, the Department of Justice, Trump, and his Lawyers.

It was reported that the white house wasn't briefed about the search warrant, and I find that perfectly plausible.

I agree that Trump's file hoarding seems more overtly intentional, but it's also not like Biden had to hide them if nobody was looking for them, which it seems nobody was

Strongly suspect that he didn't know that they were there. I'd give it more than 50% that he's responsible for them being there, but had forgotten or lost track of them after his election. Having said that, I don't know that there weren't other people at that office with some level of security clearance.