try at the beginning

data/QuickAndDirty/ubuntu-20.04/user-data

@@ -44,13 +44,14 @@ autoinstall:
         disable_root: false
 
     late-commands:
+        - apt-get update && apt-get install -y qemu-guest-agent
         - echo 'firstuser ALL=(ALL) NOPASSWD:ALL' > /target/etc/sudoers.d/firstuser
         - sed -i 's/^#*\(send dhcp-client-identifier\).*$/\1 = hardware;/' /target/etc/dhcp/dhclient.conf
 #        - 'sed -i "s/dhcp4: true/&\n      dhcp-identifier: mac/" /target/etc/netplan/00-installer-config.yaml'
         - rm -fv /var/lib/dhcp/*
 #        - systemctl restart networking
-        - curtin in-target --target=/target -- apt-get update           
-        - curtin in-target --target=/target -- apt-get install -y qemu-guest-agent
+#        - curtin in-target --target=/target -- apt-get update
+#        - curtin in-target --target=/target -- apt-get install -y qemu-guest-agent
 #         - curtin in-target --target=/target -- apt dist-upgrade -y
 # #        - sed -ie 's/GRUB_TIMEOUT=.*/GRUB_TIMEOUT=30/' /target/etc/default/grub