Thank you so much Victor!

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@Victor.Soupday  I just have a little error in the log in Unity 2020.3.37f1.   Thanks again!

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Horror Stories in VR
Immersive Sound VR
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Looks like you have a copy in your Assets folder. Don't put it in Assets, it must be installed as a package though the package manager.

Wow! this is awesome and super helpful, let me ask a probably dumb question but I'm a bit of a newby here with regards of real time engines: 
do I need to change all materials to PBR before exporting for unity? I mean, no Digital  Human Skin, hair etc?
and lastly (probably not the right thread) but is there a tool like this for C4d? this would be awesome, since this solves exactly the kind of problems me and my team are facing in C4D as well. 
Thanks so much for your help. 
please keep it up and keep on sharing!

You don't need to change the materials, there are custom shaders to match each one.

I don't know if there's anything for C4d. I deal mostly with Unity and Blender.

The latest update has resolved my retargetting issues, thanks a lot Victor.Soupday!

I also appreciate the fact that the retargetter doesn't copy any of the 'empty'  curves (curves with only 2 keys set at beginning and end with value of 0), this helps in file size and performance I assume.

The lighting presets feature is also a great addition! For perhaps more lighting preset inspiration, have you looked at the Unity The Heretic: Digital Human package? I like the presets in that package as well.

I just installed the importer, via PM and tried to import a character exported out of IClone 8. I built the materials but now the console.is spammed with a stream of errors around SSS and index outside bounds of array, and nothing is visible in screenview any more. what to do?

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I think I figured out the problem. There as already the maximum number of diffusion profiles, and the importing process added 3 on top of these, so HDRP started complaining. seems to work fine now that I took out unwanted profiles, and under the 15 profile limit

Update: I found the fix. For anyone else having this issue:
Hide the meshes with the hide mesh tool. Either painting them away with the Hide mesh tool or click on the body parts to hide them if you can with the type of clothing. I had to pain them away given the type of clothing on my character. Then, on FBX Export, check "Delete Hidden Faces". 

Here's the issue...
48% of original size (was 1060x226) - Click to enlarge

Fixed:
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Hello Victor, it might be out of scope for your plugin but that would be helpful to avoid lot of manual work:

Could you consider "Same Materials" ?
Example:

I have a character with let say Pants, accessories, vest etc. Around 15 cloth/accessories items.
I prepared those to use only 3 materials.

In CC4 Those materials are the same name and I can change the settings of one it will influence all the others. Which is good.
Once imported in Unity with your tool, I will get 15 materials. For example the accessories will be acc, acc_1, acc_2, etc.

So of course it takes a lot of space for textures etc and it's not optimized. So I'd re-assign manually 1 material to each and delete the extra mats/textures myself.
Maybe the plugin could consider this and if multiple items have the exact same Material name, it could take care of this automatically.

Do you see this as feasible?