What syncs

Each category is an independent switch in the Rhino panel.

Category

Result in Blender

Objects

Meshes, from Breps, extrusions, surfaces, SubDs and native Rhino meshes

Curves

Blender curve objects, from NURBS curves

Blocks

Collection instances

Materials

Principled BSDF, or dedicated glass / metal / emission node groups

Lights

Blender lights

Named Views

Cameras with position, orientation and lens

Text

Text objects, from Rhino annotations

Clipping planes

Plane markers with position and orientation

Layers always mirror as collections.

Tessellation happens on the Rhino side, spread across worker threads. Blender receives finished meshes.