Mister Dungeon was the first thing I made using Godot and I had a lot of "doing it the Unity way" ideas about how things should work. Since working on this, I've found that just doing a batch export from Blender into individual glb's is the easiest. For myself, I tend to set Godot to handle my textures as "embedded uncompressed" since they're so small. I found a batch export plugin for Blender where I can just select all my pieces and hit a button to get them all spit out into individual, centered, scale applied, flb files. It's much easier handling on that end compared to the import script chopping it up for me.