When I was trying to share states between islands and memorizing states while building a website using Astro.js.
Nano Stores is a tiny state manager for React, React Native, Preact, Vue, Svelte, Solid, Lit, Angular, and vanilla JS. It uses many atomic stores and direct manipulation.
https://github.com/nanostores/nanostores?tab=readme-ov-file
If you need your data to stay persistent in localStorage (by default), you can utilize this library to do the magic.