I think I will use the following workflow:
Modeling single meshes and terrain inside Blender. They are grouped into different categories like foliage, buildings etc.
One Blender project and exported file (.glb) per category.
Of course UVs are created in Blender.
Placeholder Materials in Blender (just albedo texture at max).
Import as multiple Scenes + Materials.
Map building inside Godot.
Are there any big problems I don't see right now or is there a better workflow?
Only problem I have:
If an object is imported it will also import a material and if the material already exists it will use the existing one. But can I say Godot to look in all folders for a similar material and not just in the import folder?