The thing is that your model comes from a .glb file, so it is using a PBR material: you won’t be able to match a PBR material with a node material that is using the Lights block (which corresponds to the standard material). You will have to use the PBRMetallicRoughness block instead.
If you don’t define a transparency mode, you don’t have alpha blending. As a general rule, don’t use transparency/alpha blending if you don’t need it, as there are a number of problems when dealing with transparency (see Transparent Rendering | Babylon.js Documentation) and rendering transparent objects is generally slower than rendering opaque objects because of the blending operation.