Push Ubuntu 64-bit ARM to Raspberry Pi 4

Download:
http://cdimage.ubuntu.com/ubuntu/releases/20.04/release/
Push Ubuntu 64-bit ARM:

xzcat ubuntu-20.04.3-preinstalled-server-arm64+raspi.img.xz | sudo dd bs=4M of=/dev/sdc status=progress; sync;
xzcat ubuntu-20.04.3-preinstalled-server-arm64+raspi.img.xz | sudo dd bs=4M of=/dev/sda status=progress; sync;

Connect to wifi automatically at boot up:

mount /dev/sdc1 /mnt
cd /mnt
cp network-config network-config.original
cat << 'EOF'> network-config
version: 2
ethernets:
  eth0:
    dhcp4: true
    optional: true
wifis:
  wlan0:
    dhcp4: true
    optional: true
    access-points:
      dz66:
        password: "passw0rd"
EOF
cd
umount /mnt

https://bugs.launchpad.net/ubuntu/+source/cloud-init/+bug/1870346

sda:

mount /dev/sda1 /mnt
cd /mnt
cp network-config network-config.original
cat << 'EOF'> network-config
version: 2
ethernets:
  eth0:
    dhcp4: true
    optional: true
wifis:
  wlan0:
    dhcp4: true
    optional: true
    access-points:
      dz66:
        password: "passw0rd"
EOF
cd
umount /mnt

SSH is enabled by default, can connect with::

ssh ubuntu@192.168.88.12

Change the fs commit duration:

cat << 'EOF'> /etc/fstab
LABEL=writable  /        ext4   defaults,commit=60      0 0
LABEL=system-boot       /boot/firmware  vfat    defaults        0       1
EOF