How to create mobile app UI prototypes and avoid an AI slop?

Hi all, I am new to vibe coding. I have 10 years of backend development experience but absolutely 0 years in the frontend side. I have been planning to create a cross platform mobile app using RN (Expo). For the AI slop part, an LLM answer was creating the following MD in project root: markdownpaste.com/document/avoiding-ai-slop-ui Would you agree with this? More important question is that, what would be the best way to have some UI prototypes created based on my app idea? What is your go-to while starting to development? I appreciate all your input!