Yeah - I wanted to post it here, but after searching for "linear regression explorable explanation" I got some other random links. Thankfully, I saved the PyTorch materials + https://pinboard.in/u:pmigdal/t:explorable-explanation.
This is an all-time great blog post for this line alone: "That's why we have statistics: to make us unsure about things."
The interactive visualizations are a great bonus though!
That was my initial thought, too. But I didn't know what the original Google search consisted of and the site didn't show up in a couple Kagi searches I tried. (Aside from the obvious titular one, of course.)