Recent versions of StuffIt will extract .xz archives, but they will not run on Mac OS X 10.4 Tiger. And using something like Fink, it should be possible to install xz-utils on 10.4, so that .xz archives can be extracted from the Terminal.
But is there any graphical application that will run on Mac OS X 10.4 Tiger, and which will extract .xz files?
It's OK if this application supports extracting .tar.xz archives in a single step, but not necessary, because if it extracts the .tar.xz file to a .tar file, even an older version of StuffIt can extract that.
gzip -d filename.xzalso works for me. – Huan Aug 20 '21 at 09:10