While mstar-bin-tool-master is a command-line tool, graphical alternatives do exist. MstarBinTool-GUI x86 v2.4 is a Windows-based graphical version of the MStar firmware tool. This GUI version is more accessible for beginners who may be less comfortable with the command line.
unsquashfs -d rootfs_edit output_dir/rootfs.sqsh mstar-bin-tool-master