This is my workflow :
1) model in Blender > uv-unwrap > create material
2) export as glb -without- material
3) copy the material textures to Godot
4) recreate the materials in Godot
In Godot, I keep all my textures in the 'tx' folder, and all materials in the 'mat' folder. This makes it easy to reuse materials and textures.