That was my reaction. It seems very similar (which makes sense, they're all using grammar of graphics style).

Vega Lite is very close to R's ggplot2, so we use it for our online science visualizations. The built in downloading svg/pngs built in is pretty awesome.

Vega-Lite it gets us 90% of the way there easily, the remaining 10% is always a struggle. Its well documented but sometimes lacks examples (In a side by side bar graph, how do I move the column heading to the bottom. (column->header->labelOrient: Bottom..)

We plot single cell experiment data (lots of points) and we find vegalite, very performant.

But We'll give this a look. The Javascript transforms seem nice.