cannot export .glb with material setting like specular When I export the scene as glTF 2.0 file format, it exports it with textures, but without any material information like specular-ness. I literally set it to 0 in principled BSDF, but when it's exported as glTF 2.0 .glb file it exports without that material setting.

Above is my node settings in shading tab.

And this is the result, which shows it exported without material information.
Thanks in advance.
**Solved, Thanks!
glTF 2.0's core material system uses the metallic + roughness PBR system.  You are correct that the specular channel is not currently included.  This may change in a future version of Blender, as there is a newer glTF extension proposal for including it inside of the metal/rough workflow.  But it could be some time before that appears in Blender's importer/exporter for glTF.
In the meantime, for this model you may be able to work around this by setting Roughness to 1.0.  That should make the material diffuse enough to not show any specular reflection.