I imported a simple animated glb model and I am not able to change its material or even use a physics engine.
the lighting is also not working properly, I want it to look like the babylonjs sandbox upload.
Your comments are very much appreciated.
babylonjs sandbox:
Take a look at the PBR section of the doc’, you will soon see that PBR materials need an environnementTexture 
An easy way to do this is to call the scene helper createDefaultEnvironment(), check line 3
https://playground.babylonjs.com/#ZJYNY#817
About the physics, you haven’t enabled the physics engine.
Take a look into this:
Using A Physics Engine | Babylon.js Documentation (babylonjs.com)
Enabling the engine and creating impostors for the meshes that need to have collision works fine. I just had to remove the __root__ node, but it should be simple to apply its transformation to the meshes.
[fff | Babylon.js Playground (babylonjs.com)]( fff | Babylon.js Playground (babylonjs.com))
