:android:FYI: Google compose compiler compatible with 1.9.0-Beta is already published - https://androidx.dev/storage/compose-compiler/repository

That's true, but be aware that with 1.9.0-Beta 1. the current release of the Compose Multiplatform Gradle plugin breaks Multiplatform builds (thread), 2.

@Serializable

classes won't compile on Js if the Compose plugin is present (issue KT-58911).