Mov files should display thumbnails in the file display, and play in the preview pane, if the required codes are installed:
I've found that some Mov files play with just the Microsoft codecs, but some others require LAV Filters or similar. (Both are linked in the guide.) I think the ones that needed LAV Filters were HDR ones from an iPhone.
I'm not sure where PNG files come into things. Those are images rather than videos, unless there's a special type of mov file. But Opus should also display and PNG files without any extra requirements.