Most JWs will not even know what the flashdrive is because they don't have computers. They might think it's part of a keychain, or a handle from some kind of machine lever. Or a mushroom.
But even the few who would know what it is, I think they'd just give it to an elder or MS to put in the lost and found. The elders and MS might be suspicious, since no one normally brings a flashdrive to the Hall. They will most likely think it was dropped by an "outsider".