TAKE A LOOK AT MY MUSE + WHAT THEIR LIFE LOOKS LIKE
While you wouldn't find one of those old hard drives now, they were very telling of who Pavel was as a person at those various times. Sentimental as he is, he is the type to transfer over whatever data he deems important and then destroy the drive in a way that prevented it from ever being accessed again.
On an old hard drive you'd find a dual-boot environment of both Linux and Windows (or insert future versions of these who knows what they're running then) with him favouring the former.
You'd find a crazy amount of songs saved to a music folder filled with a whole bunch of subfolders set up the way he wanted it.
Books. You'd find so many totally legally obtained books, be they poetry books, sci-fi, classic lit, textbooks in subjects he's interested in, you name it. And the craziest thing about that is that he actually managed to read almost all of the books he had on there.
There would be a number of documents that at first glance wouldn't make sense unless you had some insight into his (since mostly abandoned) illegal doings online. In addition to that, you'd find drafts of old university projects, notes for things he wanted to accomplish (occasionally written either too fast or at some ungodly hour that see them filled with various grammatical/spelling errors), applications, and other various things. Some of them with the weirdest filenames.
You'd find a copy of a Russian - English dictionary that he downloaded when he was like alright, I need to start learning if I'm going to Starfleet. And you'd find some example things he started writing in the earlier days of his learning that he'd be mildly embarrassed now to ever have seen by another living person.
You'd find his old handle on whatever the 23rd century equivalent of Reddit is. Don't ask him about it he'll deny everything. An internet search history that showed him going down some wild rabbit holes out of sheer curiosity.
A couple games. An emulator or two. He's not the biggest gamer but he's played some things in his time. He enjoys some RTS games, strategy games like XCOM or Fire Emblem even. Mass Effect he would get invested in. He's good at strategy, it keeps him sharp, and puzzling things out is fun for him.
Pictures. So many pictures. Whether they're saved from the web, scanned in copies just in case, ones he took himself during the course of his life or just awful memes that have made him laugh, there's a treasure trove of stuff in those various photo folders.
Music editing software, content editing software, some films, encrypted folders that hold things he wouldn't want others to see... His drives are huge and well used.