I've just finished porting over my Gmenu2x skins from the GP2X and Dingoo to the GCW Zero. For the most part they're operating system based skins and have custom icons for the section, applications, and UI as well as wallpapers. So far I have: Amiga OS 4, Aros, BeOS, Mac OS 9, OS/2 Warp 4, QNX, Windows 3.1, Windows XP, and one based on the old PC game Star Wars Yoda Stories.
Just download, unzip, copy into the /media/data/local/home/.gmenu2x/skins folder on your Zero and you're all set!https://drive.google.com/drive/folders/1pRIQRI-oRHrNDSgAD2VcQX-wHAvykBIw?usp=sharing
PM me with any problems, suggestions, or questions.