At an old startup attempt we once created a nested hierarchy metrics visualization chart that I later ended up calling Bookshelf Charts, as some of the boxes filled with with smaller boxes looked like a bookshelf (if you tilted your head 90 degrees). Something between FlameGraphs and Treemaps. We also picked “random” colors for aesthetics, but it was interactive enough so you could choose a heat map color for the plotted boxes (where red == bad).

The source code got lost ages ago, but here are some screenshots of bookshelf graphs applied to SQL plan node level execution metrics:

https://tanelpoder.com/posts/sql-plan-flamegraph-loop-row-co...

Very neat. And if anyone from Plotly should happen to be reading this, a compact format like this might be an interesting option for Icicle Charts, akin to how the compact, indented version of Excel pivot tables saves horizontal space over the "classic" format pivot table.

Thanks for sharing, that is a neat in-between.