Idml file type doesn't unzip using Mac Archive Utility

Another update:

When in InDesign run the ExtendScript code below from InDesign's Scripts panel.

Should work in Windows and on macOS:

/*
	ExtendScript code. Run the script file with suffix *.jsx from InDesign's Scripts folder.

	Select an IDMS file through an open dialog.
	The file will be unzipped to a folder with the name of the IDML file without the suffix.
*/

var getIDMLFile = File.openDialog
(
	"Open InDesign IDML File" ,
	"*.idml",
	false
);

if( getIDMLFile == null )
{
	alert( "NO FILE SELECTED." );
	exit();
};

if( !getIDMLFile.name.match(/\.idml$/) )
{
	alert( "Selected file is not an IDML file." );
	exit();
};

try{
	var targetFolder = Folder( getIDMLFile.parent +"/"+ getIDMLFile.name.replace(/\.idml$/,"") );

	// Unpack IDML file:
	app.unpackageUCF( getIDMLFile , targetFolder );
}catch(e)
{
	alert( "Could not unzip file." );
	exit();
};

alert( "Done" );

Note: tested with InDesign 2024 version 19.5.0.84 on macOS.

Additional note: The script is also working with InDesign 2025 version 20.1.0.71 on macOS.

Regards,
Uwe Laubender
( Adobe Community Expert )

Somewhat aside, but ZIP is an extremely mature, stable and nearly universal format. I'd have questions about any modern tool that cannot unzip any current variation. I haven't needed alternate versions since.... the 1990s?

IDML file is a "basic" ZIP archive.

I'm not a Mac user - but can't you assign IDML extension to your preferred unzip'ing tool?