I’ve been experimenting with this, it’s a very interesting problem space!

https://github.com/evelant/synchrotron

Idea is to sync business logic calls instead of state. Let business logic resolve all conflicts client side. Logical clocks give consistent ordering. RLS gives permissions and access control. No dedicated conflict resolution logic necessary but still guarantees semantic consistency and maximally preserves user intentions. That’s the idea at least, requires more thought and hacking.