[Google Pixel 2 XL ROMs, Kernels, Recoveries, & Oth] 73sydney:
fwiw, here is the updater-script for NikGapps full

#!/sbin/sh
# Shell Script EDIFY Replacement

#Variables
OUTFD=/proc/self/fd/$2;
ZIPFILE="$3";
COMMONDIR=/tmp/AFZCScripts;
TMPDIR=/dev/tmp
NikGappsAddonDir="/system/addon.d/nikgapps"

addToLog() {
echo "$1" >> "/tmp/NikGapps.log"
}

decrypt() {
mkdir -p "$(dirname "$2")"
addToLog "- decrypting $COMMONDIR/busybox"
addToLog " -> source $1"
addToLog " -> destination $2"
unzip -o "$COMMONDIR/busybox" "$1" -p >"$2"
chmod 755 "$2";
}

ui_print() {
until [ ! "$1" ]; do
echo "ui_print $1
ui_print" >> "$OUTFD";
addToLog "$1"
shift;
done;
}

# package_extract_file <file> <destination_file>
package_extract_file() { mkdir -p "$(dirname "$2")"; unzip -o "$ZIPFILE" "$1" -p > "$2"; }

# package_extract_dir <dir> <destination_dir>
package_extract_dir() {
local entry outfile;
for entry in $(unzip -l "$ZIPFILE" "$1/*" 2>/dev/null | tail -n+4 | grep -v '/$' | grep -o " $1.*$" | cut -c2-); do
outfile="$(echo "$entry" | sed "s|${1}|${2}|")";
mkdir -p "$(dirname "$outfile")";
unzip -o "$ZIPFILE" "$entry" -p > "$outfile";
done;
}

#-----------------------------------Execution Starts---------------------------------#

package_extract_file "tools/busybox" "$COMMONDIR/busybox"

decrypt "nikgapps_installer" "$COMMONDIR/nikgapps_installer"
decrypt "ak3mount" "$COMMONDIR/ak3mount.sh"
decrypt "addon" "$COMMONDIR/addon"
decrypt "header" "$COMMONDIR/header"
decrypt "functions" "$COMMONDIR/functions"
decrypt "nikgapps.sh" "$COMMONDIR/nikgapps.sh"
decrypt "file_size" "$COMMONDIR/file_size"

rm -f "$COMMONDIR/busybox"

# Mount the partitions
. $COMMONDIR/ak3mount.sh
# Install the stuff
. $COMMONDIR/nikgapps_installer "$2" "$3"
show_progress 1.00 0

# Store the size of partitions before installation starts
df > "$COMMONDIR/size_before.txt"
df -h > "$COMMONDIR/size_before_readable.txt"
# Setting up tools
SetupTools

if [ $(initialize_app_set "Core") = "1" ]; then
install_the_package "Core" "ExtraFiles"
set_progress 0.02
install_the_package "Core" "GooglePlayStore"
set_progress 0.04
install_the_package "Core" "GoogleServicesFramework"
set_progress 0.06
install_the_package "Core" "GoogleContactsSyncAdapter"
set_progress 0.08
install_the_package "Core" "GoogleCalendarSyncAdapter"
set_progress 0.1
install_the_package "Core" "GmsCore"
set_progress 0.12
else
ui_print "x Skipping Core"
fi
install_the_package "DigitalWellbeing" "DigitalWellbeing"
set_progress 0.14
install_the_package "VancedManager" "VancedManager"
set_progress 0.16
install_the_package "GoogleMessages" "GoogleMessages"
set_progress 0.18
install_the_package "GoogleDialer" "GoogleDialer"
set_progress 0.2
install_the_package "GoogleContacts" "GoogleContacts"
set_progress 0.22
install_the_package "CarrierServices" "CarrierServices"
set_progress 0.24
install_the_package "GoogleClock" "GoogleClock"
set_progress 0.26
if [ $(initialize_app_set "SetupWizard") = "1" ]; then
install_the_package "SetupWizard" "SetupWizard"
set_progress 0.28
install_the_package "SetupWizard" "GoogleRestore"
set_progress 0.3
install_the_package "SetupWizard" "GoogleOneTimeInitializer"
set_progress 0.32
else
ui_print "x Skipping SetupWizard"
fi
if [ $(initialize_app_set "Pixelize") = "1" ]; then
install_the_package "Pixelize" "PixelSetupWizard"
set_progress 0.34
install_the_package "Pixelize" "AndroidMigratePrebuilt"
set_progress 0.36
install_the_package "Pixelize" "PixelTips"
set_progress 0.38
install_the_package "Pixelize" "PixelConfigOverlays"
set_progress 0.4
else
ui_print "x Skipping Pixelize"
fi
install_the_package "GoogleCalculator" "GoogleCalculator"
set_progress 0.42
install_the_package "Drive" "Drive"
set_progress 0.44
install_the_package "GoogleMaps" "GoogleMaps"
set_progress 0.46
install_the_package "GoogleLocationHistory" "GoogleLocationHistory"
set_progress 0.48
install_the_package "Gmail" "Gmail"
set_progress 0.5
install_the_package "GooglePhotos" "GooglePhotos"
set_progress 0.52
install_the_package "DeviceHealthServices" "DeviceHealthServices"
set_progress 0.54
install_the_package "Velvet" "Velvet"
set_progress 0.56
install_the_package "GBoard" "GBoard"
set_progress 0.58
if [ $(initialize_app_set "PixelLauncher") = "1" ]; then
install_the_package "PixelLauncher" "PixelLauncher"
set_progress 0.6
install_the_package "PixelLauncher" "DevicePersonalizationServices"
set_progress 0.62
install_the_package "PixelLauncher" "QuickAccessWallet"
set_progress 0.64
else
ui_print "x Skipping PixelLauncher"
fi
if [ $(initialize_app_set "GoogleFiles") = "1" ]; then
install_the_package "GoogleFiles" "GoogleFiles"
set_progress 0.66
install_the_package "GoogleFiles" "StorageManager"
set_progress 0.68
else
ui_print "x Skipping GoogleFiles"
fi
install_the_package "PlayGames" "PlayGames"
set_progress 0.7
install_the_package "GoogleCalendar" "GoogleCalendar"
set_progress 0.72
install_the_package "MarkupGoogle" "MarkupGoogle"
set_progress 0.74
install_the_package "GoogleWallpaper" "GoogleWallpaper"
set_progress 0.76
install_the_package "GoogleFeedback" "GoogleFeedback"
set_progress 0.78
install_the_package "GooglePartnerSetup" "GooglePartnerSetup"
set_progress 0.8
install_the_package "GoogleSounds" "GoogleSounds"
set_progress 0.82
install_the_package "AndroidDevicePolicy" "AndroidDevicePolicy"
set_progress 0.84
install_the_package "GoogleKeep" "GoogleKeep"
set_progress 0.86
install_the_package "Books" "Books"
set_progress 0.88
install_the_package "Assistant" "Assistant"
set_progress 0.9
install_the_package "YouTubeMusic" "YouTubeMusic"
set_progress 0.92
install_the_package "GoogleRecorder" "GoogleRecorder"
set_progress 0.94
install_the_package "GoogleTTS" "GoogleTTS"
set_progress 0.96
install_the_package "GoogleTalkback" "GoogleTalkback"
set_progress 0.98
install_the_package "DeviceSetup" "DeviceSetup"
set_progress 1.0
install_the_package "AndroidAuto" "AndroidAuto"
set_progress 1.0
if [ $(initialize_app_set "GoogleChrome") = "1" ]; then
install_the_package "GoogleChrome" "GoogleChrome"
set_progress 1.0
install_the_package "GoogleChrome" "WebViewGoogle"
set_progress 1.0
install_the_package "GoogleChrome" "TrichromeLibrary"
set_progress 1.0
else
ui_print "x Skipping GoogleChrome"
fi

set_progress 1.00

exit_install