Flutter maintains 3 trees - Widgets, Elements, and Render Objects. The user only sees Widgets though unless they are going lower-level. I’m curious if compose maintains several trees as well. Does it?

At the moment, no. Compose UI forms a single tree of ComponentNodes. That said, we have explored this type of architecture a bit but decided not to go down this route, though may revisit at a later date.

if you're looking for a (very) rough equivalence mapping, the call graph in compose serves the purpose of flutter's widget tree, the slot table serves the purpose of the element tree, and the ComponentNode tree serves the purpose of the renderobject tree.