Going further afield into tangent, I love the looks of these "subway diagrams" of the commits, but I keep thinking that as great as they look and as nice screenshots as they make what I'd love to see a Git UI do is something very different: take a --first-parent approach by default and use a drilldown/expandable view of commits past first parent. It would look a lot more boring in screenshots, but could be a great way in practice to ease people into the two dimensional git DAG without making it seem so messy/busy by default. Many projects it would provide a good "PR focused" view of the repository up front and center (without being reliant on specific PR tools/APIs, only that those PR tools create merge commits).

Going off to a different tangent: the vertical colored lines down the side of a list of chronologically ordered items to show reply threads was a visualization I first spotted in the early oughts or late 90s from a showcase of Microsoft Research Visualizations and so Microsoft Research has published research and had patents on it at one time. Those patents have all since expired, I believe, but it's interesting to note that it was on some minds even back then, which was neat, and curious to wonder what if a Microsoft product had embraced it earlier. (I recall the demo felt a lot like Outlook's email list and the impression was that was what they were trying to sell it as a possible tool to the Outlook team. Which seemed a neat idea for email visualization, though I think Outlook decided that strict temporal ordering wasn't necessary for reply threading that users were happy enough with.)