I decided to give the walkthrough video a careful look and… you’re just supposed to be able to pick it up? Is there some sort of prerequisite I might be missing? Or is this a bug?
Update: okay, I have learned now that the white dot does not appear on some objects for me. It’s happening with the broom closet key as well. Maybe it’s because I’m playing it through Proton on a Steam Deck, though I’d find it odd if that makes me unable to pick up some arbitrary items. I’m going to play around and see if I can’t get this to work.