In our case that would be hundreds of geometry nodes, I imagine we need a different approach. I was looking into using instances instead but I'm not sure if each instance gets it's own independent transforms or if they show up as a group with a single central transform to all instances.
As far as the object level geometry node. You can set up a houdini python script to do this. The SideFX Labs static fracture export will do this for the static frames. You will need to add this to bottom of your SOP network, and adjust the script so it writes it within an editable object level HDA.
You can do instances too. Instances will be more performant than as geometry nodes are straight GameObject conversions. You can use the Copy To Points sop node set to pack, or use the instancer at object level. The former setup is quick and straightforward. The later is more complex but more scalable. EDIT: this method does give each instance it's own transform like you were asking
A third option is to use the Tree or Prefab instancer https://www.sidefx.com/docs/unity/_terrain.html#Terrain_Scatterring. I do not believe this will carry the parent transform though as originally requested.