In PaperDoll's SetTexture you need to change the line to:
if (!texturePath.Equals("") && !texturePath.Equals(TexturePath))
Currently, that ! is missing on the textureParth.Equals, so if someone tries to swap the sprite texture at runtime it will fail to set the TexturePath.
p.s. Love all of your products, I've grabbed them all. How are things coming on an update for the farmer pack (also they have a wider range of ramps for farmer, so you'd need a new shader pack for that), eye updates and weapons, etc? Also, SpriteImporter probably needs an update soon as they've changed the API again for Unity 6. Looks like they're giving us a lot more control over the importer and they've been refactoring it.
I've made a convenient slider for your material pack:
Also, regarding the shader pack you should probably upload a version for Unity 6 which has the ramps fixed. I fixed them on my side but it'll reduce confusion to just have them set correctly in a separate package download. Sorry for merging all my comments into one on this kind of unrelated thread.