Hi I am assuming you have already built your model and created the corresponding textures, why not try model converter X development version. Create a new folder, put your gltf file with its corresponding bin and xml file in there, then create another folder and call it texture ( must be inside the same folder) and import your gltf file in to model converter x and see what happens. This tool was kindly donated by the Great Arno of fs developer fame and it is very good and free!
In model converter you can also check what textures are missing and try and link them to your gltf file and re-export it as gltf, it is a very powerful tool.
Don’t forget it can also compile and create MSFS package from your source file.