jpackage
It does all of this work for you and its a standard tool that dumps out a platform specific application bundle.
The only people living in 2010 are the ones that choose to live there with incredibly outdated takes on things they dont understand.
Has jpackage been updated to create things that are not installers and don't extract themselves into several files?
Bundling the JRE in the bundle typically results in something that is not redistributable with the default OpenJDK license: The Java ecosystem is heavily tilted towards the Apache license, but Hotspot is licensed under the GPL v2 only (no classpath exception). The Apache license and older GPL versions (before 3) are generally assumed to be incompatible.