What it says on the tin!

It'll let people make dummies of their own of any skin without having to rely on a specific user wearing that specific skin.

I've been vaguely eyeballing mods for the past few weeks, and I do wonder how this would actually function in a server/client situation. Will both need the datapack? I know there's a 'server datapack' option you can potentially enforce, though having download space for those packs isn't always simple.