Very nice. I’ve used Loess regression ten years ago when charting my body weight with R. Here is the blog post about it:
https://blog.tafkas.net/2013/06/22/five-years-of-weight-trac...
https://blog.tafkas.net/2013/06/22/five-years-of-weight-trac...
Edit: I misremembered, it evaluates 80 predictions to draw the line, which is why you can't retrieve the formula from the plot object anymore, but it does in fact fit on the whole dataset.
Loess regression does have n^2 memory complexity, but the cutoff it uses to decide to go for a different model family is n >= 1000.