For screenshots you could just link to one of the implementations, those give at least some indication of what the themes look like. For example: https://github.com/catppuccin/emacs
I suppose it looks decent, but I'm not fond of themes which make comments hard to read.
See https://github.com/catppuccin/catppuccin or https://catppuccin.com/ . I wish they included screenshots, it's really hard to say 'check out this theme' without being able to link one. And I can't screenshot the code I have available in VSCode ;)