Not 100% related but it seems compose desktop needs java 11. I thought I could just specify that in gradle:

java {
    toolchain {
        languageVersion.set(JavaLanguageVersion.of(11))
    }
}

But when running from the command line:

./gradlew run

It shows an error:

Exception in thread "AWT-EventQueue-0" java.lang.UnsupportedClassVersionError: org/jetbrains/skiko/Library has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0

I suppose the Kotlin Gradle plugin must be changed to take Gradle Java Toolchains into account before this can work out of the box https://youtrack.jetbrains.com/issue/KT-43095

Also note that you need Java 14+ to build native executables

This worked for me: https://github.com/JetBrains/compose-jb/tree/master/tutorials/Native_distributions_and_local_execution#customizing-jdk-version

guess setting JAVA_HOME shall help

Yeah for me too. But I love how the project is self contained and reproducible when you just set the jdk version in gradle.

to package it, you need Java 15