pgvecto.rs is a Postgres extension that provides vector similarity search functions. It is written in Rust and based on pgrx. It is currently in the beta status, we invite you to try it out in production and provide us with feedback. Read more at 📝our blog.
Because there is no stable release. Any update can have breaking changes since it is beta software like immich itself.
You could just use syncthing to sync between devices. Works like a charm.