You can edit posts, adding tags like that is done to provide commentary on the post that doesn’t get attached to further reblogs (unless someone copies it into their own reblog addition like in the screenshot here)

It is not quite a native binary, but the effect of not having to install java to run it is the same. Using jlink you can assemble a runtime image containing the java bytecode for the application and a custom runtime enviroment containing the parts of the the jre needed to run that program.