https://forum.inaturalist.org/t/widget-logo-filename-keeps-changing-and-breaking/26042.
the link above references a recent forum discussion where someone mentions that they use the widget on their (Wordpress) site. you can go to iNaturalist (not the Forum), and look for that person’s profile and find their website.
what are you trying to do? are you just looking for how someone else implemented the widget?