Yes, pretty much all treemap disk space tools I've used will perform color gradient grouping on boxes, with directories fitting in larger boxes. The box may not be drawn, but the inner boxes will align, visually making a larger box. Also, mouse hovers go a long way.

Like, one just has to look at the qdirstat screenshot at https://github.com/shundhammer/qdirstat. On the bottom-right corner, there are visually distinct boxes of sub-boxes that guide the eye towards a logical set of files.