I got a model of a ship as an FBX. I'd like to keep the materials it has, but I don't need any hierarchy. I'm not sure why, but when I import the FBX (only "Geometry" and "Materials" selected in the FBX dialog), I get a huge network of 100s (maybe 1000s) of separate geometry objects. Within each one is a single File SOP. All of these objects are linked to a single "Model" object. Some of these individual "objects" are ridiculously small, e.g. pointing to just 2 polygons etc. It's too much to handle (do ships really need any hierarchy at all?). Can I import this FBX as a single geometry model, yet keep the materials? Alternatively, can I "collapse" the huge object hierarchy I have now and save it to a single geo file? There is no "Save as geometry" at the object level. I tried exporting to FBX and re-importing but I get the same huge hierarchy.

you could import it once as you did, then dive in and only keep the generated material network. Then use a normal filenode to read the fbx as a single object, it should have an fbx material path attribute that you can wrange to point to the generated materials in the network from the initial import.

Thanks, it worked. The "Materials" object is also quite something: ~300 separate principled shaders. At least it's not geometry and I don't have to dive into it.