pubkey/rxdb ? reverse-engineered prompt

I'm looking to build a JavaScript application that feels really fast and responsive because it's "local-first." The main idea is that all the data should be stored on the user's device so the app works perfectly even when they're offline. Then, when a connection is available, it should automatically sync changes.

The most important feature is real-time collaboration. When one person makes a change to some data, other users should see it update on their screen instantly, without anyone needing to refresh the page. Think of how Google Docs works.

This should be built with JS or TypeScript and needs to be flexible enough to run in a web browser, in a Node.js backend, and also on mobile with something like React Native. For the data syncing, I want to be able to connect it to various backends, like a custom GraphQL API or services like Supabase or even Firestore.