extract ipsw root file system on linux

ipsw-extract.sh

#!/bin/bash

USAGE=$'extract ipsw root file system on linux
usage: ipsw-extract.sh iPhone_Restore.ipsw
requires apfs-fuse - https://github.com/sgan81/apfs-fuse'

if [ -z "$1" ]; then
  echo "$USAGE"
  exit 1
fi

mkdir extract
unzip "$1" -d extract
cd extract
#ramdisk is the largest file
RAMDISK="$(find . -maxdepth 1 -printf '%s %p\n' | sort -nr | head -n 1 | cut -d' ' -f 2-)"
echo "ramdisk filename: $RAMDISK"
mkdir mount
sudo apfs-fuse "$RAMDISK" mount
MOUNT_FULL="$(readlink -f mount)"
echo "ramdisk mounted on $MOUNT_FULL"
echo "to unmount, run sudo fusermount -u $MOUNT_FULL"

Is this for macOS?

no, but you could do a similar procedure on macos