To be clear, you did not need to have purchased or played BG3 at all to vote for it in the steam awards, and I personally witnessed numerous people who openly said they were going to vote for it in every category they could, regardless of the category, and regardless of whether or not they'd gotten around to playing the game yet (back logs, other games, etc.), because 'they were sure it was great' or they'd 'heard great things about it'.
Not to discount the reports and the statements made, but, drawing speculation about sales count based on award votes is just that - extremely speculative and unreliable.