My two cents would be to stay focused - there are a ton of general image search resources online. unsplash.com for example seems hard to beat. One place to consider expanding to would be CSS animated gradients though.
In terms of generating code: - Android - iOS (objective-c + swift) - React Native - Flutter
seem like the most popular non-CSS based mobile frameworks.
Re:Show HN: GradientMagic
by TedDoesntTalk on Sunday August 16, 2020 @03:56PM
(#24180702)
I’d love to see these paired with css animations for subtle background changes between gradients.
Maybe that’s premium content. I’m not sure how useful it is to designers since I am not one.
I'd be curious as to what other non-css formats would be helpful. You mention Flutter LinearGradient, are there others? SVG certainly, is there a way to make images export friendly for Sketch or Figma?