Same, I've added a .#screenshots derivation. High up-front effort but almost zero maintenance afterwards.

Bonus: since you're generating screenshots programmatically anyway, you can generate a pair of each with your app's light/dark theme, and swap them in/out depending on prefers-color-scheme: dark. <picture> elements work in GitHub READMEs, too: https://github.com/CyberShadow/CyDo#readme