PubSub and LiveView do go a long way. However, broadcast isn't sync and LiveView isn't appropriate for all applications.

Phoenix recently added Phoenix.Sync [0], a sync engine library explicitly designed [1] to address this. In combination with a front-end library like TanStack DB [2] it goes much further towards giving you a Figma/Linear-style sync engine out of the box [3].

[0] https://hexdocs.pm/phoenix_sync [1] https://www.youtube.com/watch?v=4IWShnVuRCg [2] https://electric-sql.com/blog/2025/07/29/local-first-sync-wi... [3] https://electric-sql.com/demos/burn

Disclaimer: Electric founder. Linking to my own talk / post / demo.

A sync engine plus the always online nature of LiveView feels at odds with offline-first (which is often associated with sync engines). I wish LiveView had a better offline story.