I once built a mind map with a “MUSH” interface (text-based, where you traverse the map “on ground level” as a character). You avoid information overload by showing the synopsis as you “enter” a node, then you could say `e[xamine] here` to view the whole text.

Traversal is quicker than you’d think, and it would likely work well on mobile devices.

It was years ago, but I still think about making that in to something “real”.