Best I can do is video game skyboxes on PixelFed https://pixelfed.social/videogamesskies

Edit: apparently this link got posted by itself on HN and someone else linked to the HN post replying to your question.

After reading the article I googled for “samurai jack art style guide” and found this (it has a bunch of backgrounds part way down): https://characterdesignreferences.com/art-of-animation-8/art...

May I also recommend ren and stimpy in this category ? Beyond that you may even have to go back to looney tunes for more watercolor style layering.