Transferring textures to Blender/Unity

I have been retopologizing very heavy, dense mesh assets created in Oculus Medium in order for them to be usable in animation and as game assets in Unity. My only quibble is that once I have retopologized the asset, the way that the medium textures export no longer works properly. The textures are broken up into a bunch of little islands and there is no way to export them another way except to export the asset with vertex colors, but then I can't use metallic and emissive materials.

Here is an example of what the exported textures look like:

(the unity symbol thumbnails are previews that prove useless when I try to open them in Unity)

this is what the above textures look like in medium:


and this is what it looks like in Unity with the provided texture applied:

When imported into blender, I see no sign of a texture file or material, even when I export the asset with vertex colors, it still imports with no color. This is an example of the same asset as above imported into Blender:

I know that if I could just get the object into blender with its textures/materials in tact, I could bake the materials and be fine besides not being able to use emissive and metallic materials, but I would at least like to be able to use the textures that I hand-painted in VR without having to re-create them in blender. As you can see from the first image, it comes with normal maps too which is great in theory, but I cannot use anything but the mesh in blender, and once that is retopologized, the textures become useless and the normal maps don't work in Unity either way.

I know that not a lot of people here have experience with medium, but I am just SO close to being able to sculpt and paint in VR then make my creations come alive in Unity if not for this one stubborn recurring problem.

Apologies for the long post and redundancy, any assistance would be wildly appreciated!