MY prototype tree map nav element is 2D - a plane. You can scroll around and zoom in. It seems good to me. On the other hand, there is a level of complexity that I still do not really understand. What about a cube with a different tree map (or other?) on each face. A rotatable cube does not break the paradigm. (Or a dodecahedron for that matter.)

Another thing I am thinking about is how will the user transition "into" a place? For example, a user finds email on the tremap and now wants to send one. What is the transition to writing an email? The kind of transition is the part I am curious about.

I personally find the concept of going "into" a place most appealing. It makes intuitive sense to me. I zoom into a building in NYC and click on it and I am now "in the place". But the tech part of me says "oh just do an overlay, make the canvas div hidden and put up a little text entry form". Does it matter?

I suspect but do not know that keeping the paradigm => going into a place on the map => would be more engaging, comprehensible, user friendly than suddenly breaking the illusion. But I am just guessing.

[ And did you look at the image gallery example?

https://lx2h8.csb.app/

clicking on a panel takes you up close. It is pretty easy to add a feature so that when up close another click goes "into the panel". To a room of other panels or objects. ]