https://imgur.com/a/woL8b8j
You're right. But. I think overall by this point we should be able to sort everything out. Mostly. I parsed the illustration template and packed up all the brushes-textures so far it did double the filesize to 20mb. The rest of the file was untouched.
I think. Because I just tried it on my potato Microsoft Surface. Its how Blender sorts the image textures and brushes. It will kick out some of the brushes like. The first time. The brush textures are there. Duplicate a default brush. Rename. Attach the material. Go on with life. Here the linked template file on my Google Drive.
All the brushes Illustration Template