In general, many of the material node configurations Blender allows cannot be exported to any standard format. They are specific to Blender, and can only be rendered in Blender. See this article for background on the problem: https://blender.stackexchange.com/questions/57531/fbx-export-why-there-are-no-materials-or-textures.
When exporting to glTF, use the Principled BSDF node in Blender and follow the guidelines here: https://docs.blender.org/manual/en/2.80/addons/io_scene_gltf2.html. This particular material type is well-supported in Blender, fits well into glTF, and fits into the PBR material systems in modern engines. For something like a color ramp, you’ll likely need to convert it to a texture or vertex colors, or re-create that particular part in your code after loading the model.
Baking a diffuse map in Blender might also be an easy escape hatch, on this particular example.