I am currently thinking about a solution.
I will also have to update in the same time all the other software and add-ons I created. e.g. all Blender add-ons, Mecabricks render mode, etc.

Adding glitter might become even more complicated with the latest City-Space Port models from Lego. Many sets have the so-called Rock-Crystal (https://brickset.com/parts/6259944/rock-crystal-no-1002) this part does not only have glitter but also a second solid color.
This would also require an additional material for decorations with glitter. Or is it possible that a brick model can consist of multiple meshes with each having a different material?

Multimaterial parts become more common nowadays. I am thinking about solutions that would be retrocompatible as I do not want to update existing elements. It is also tricky when a part has multiple materials and is decorated as well. Quite a few challenges ahead to find the the right solution.

Actually i'm currently working on some models which i wanted to send you (some models for the City Space Port series) and also stumbled upon the missing glitter for the above mentioned part, so i played around with the mv_decoration shader in blender a bit and found a solution that seems to work at least for me quite well:

It also works for normal parts:

The glitter effect is enabled only be a certain combination of the alpha channel and the metal map. More precisely when the metal map is set to chrome (0xFFFFFF) and the alpha channel is below 90% it enables the glitter effect for the transparent sections which have the chrome setting.
I have not seen that this kind of combination is used for any other official effects right now and should therefore be retrocompatible.
The glitter is also independent of any UV map so it does not need changes for already existing parts or interacts with UV mapped models.

If you like, i can send you the .blend file where i played around with the glitter shader.

You can already find a glitter material in the Mecabricks add-on. It is called mb_glitter. I didn't put too much effort into it and I plan a rework with volumetric glitter in the future.

PS I have official base meshes and decorations for the new city sets that I have to rework as well. I checked your files in the drop box and there are a couple of little things to correct. I'll make my report soon. If you wish, you can give me your email address in private message and I'll send you some files.

PS2 Happy to look at you models and blend files as well. It looks good.

Heh, i never realized that there already is such a material. I just expected that there is none because its not in the workshop, so i never actually looked for it. All in all the approach from mb_glitter is quite similar. Volumetric glitter sound like a while new level.

Wrote you an email 😉

Thanks. I am away for the weekend. I'll answer properly and I'll attach all the requested files when I am back.

Very cool, thanks a lot! No need to hurry, i'm busy until mid next week anyway 😉