My app is for chat-based notes[1] and I have been wanting E2E local-first sync on it for a while. Switched from Realm to SQLite after it was deprecated but never found a good non-niche DB SDK for it on Flutter. Tried to handroll sync + AES-GCM encryption with Supabase Realtime and it kind of worked but I knew managing encryption was going to be hell and also wanted collaboration features. Matrix was built for chat, and at some point I read someone call it basically a graph sync engine & potentially supporting general texting with other clients also seemed like a cool bonus.

That said, adopting it (even partially) was/is a big mess, there's a thousand corner cases with key exchange, etc. so it's really a big commitment, especially if there's no existing user-friendly SDK for it.

I'm not using yjs (yet), just going to more basic event sourcing that is essentially last-write wins but that's a direction I want to explore in the future.

[1] https://tetrify.com/