Quick follow-up on my earlier comment. The materials in this pack's Blender file use Diffuse BSDF nodes instead of Principled BSDF. Blender's glTF exporter is built specifically around reading Principled BSDF to translate textures into the exported material. it doesn't recognize Diffuse BSDF, so it drops the texture link and only exports the base color as a flat value. That's why everything imports with a material name attached but no actual texture. I swapped those nodes to principled and I can use them in Godot now! yay :)