Missing Shader nodes on Blender 2.91.2 Export

[AlphaLuceatLaetis]

OS:
Linux Mint 19.1 x64 bit

Godot version:
3.2.3 Official Stable Version

Blender version:
2.91.2 Official Release Version

Issue description:
I made a model for a game, once export I had a few warnings (see image) and some shader nodes seems missing since the material is incomplete/wrong.
I attach the Blend file so you'll be able to see in more detail.
Thanks for helping with this bug!

Minimal reproduction project:
IlRubega.blend.zip

[AlphaLuceatLaetis]

Hi all, do tell me if there is something else I can do to help with this bug.
I'm new around, so I don't know what else to do to help.

[Calinou]

Hi all, do tell me if there is something else I can do to help with this bug.
I'm new around, so I don't know what else to do to help.

This exporter only has a few contributors working on it, and they may be busy working on other things. I recommend trying out glTF 2.0 instead.

[AlphaLuceatLaetis]

I tried, but I still have the same problem with the material resulting in a simple white/non-colored one.
It seems that I'll have to wait for this bug to be fixed.
Thank you for your time.