Upgrade and sync your Homebrew installations between Macs (Intel and Silicon M1/M2) via iCloud (including casks). You only need to chmod +x and run.

brewsync

#!/bin/bash

# Sync Homebrew installations between Macs via iCloud
# Working on Intel and Silicon Macs

# Target folder on iCloud
TARGET="Homebrew"

# Homebrew binary path by platform
if [[ $(uname -m) == 'arm64' ]]; then
	BREW="/opt/homebrew/bin/brew"
else
	BREW="/usr/local/bin/brew"
fi

# Path to target folder
ICLOUD="$HOME/Library/Mobile Documents/com~apple~CloudDocs/$TARGET"
# Check if the target folder exists. If not, then will be created.
if [ ! -d "$ICLOUD" ]; then
	mkdir "$ICLOUD"
fi

# upgrade first
$BREW upgrade

# first get local settings
echo "Reading local settings ..."
rm -f /tmp/brew-sync.*
$BREW tap > /tmp/brew-sync.taps
$BREW list > /tmp/brew-sync.installed
$BREW list -1 --cask > /tmp/brew-sync.casks

# then combine it with list in iCloud
echo "Reading settings from iCloud ..."
[ -e "$ICLOUD"/brew-sync.taps ] && cat "$ICLOUD"/brew-sync.taps >> /tmp/brew-sync.taps
[ -e "$ICLOUD"/brew-sync.installed ] && cat "$ICLOUD"/brew-sync.installed >> /tmp/brew-sync.installed
[ -e "$ICLOUD"/brew-sync.casks ] && cat "$ICLOUD"/brew-sync.casks >> /tmp/brew-sync.casks

# make the lists unique and sync into iCloud
echo "Syncing to iCloud ..."
mkdir -p "$ICLOUD"
cat /tmp/brew-sync.taps | sort | uniq > "$ICLOUD"/brew-sync.taps
cat /tmp/brew-sync.installed | sort | uniq > "$ICLOUD"/brew-sync.installed
cat /tmp/brew-sync.casks | sort | uniq > "$ICLOUD"/brew-sync.casks

# Set taps
echo "Enabling taps ..."
for TAP in `cat "$ICLOUD"/brew-sync.taps`; do
	$BREW tap ${TAP} >/dev/null
done

# Install missing Homebrew packages
echo "Install missing packages ..."
for PACKAGE in `cat "$ICLOUD"/brew-sync.installed`; do
	$BREW list ${PACKAGE} >/dev/null
	[ "$?" != "0" ] && $BREW install ${PACKAGE}
done

echo "Install missing casks ..."
for CASK in `cat "$ICLOUD"/brew-sync.casks`; do
	$BREW list -1 --cask ${CASK} >/dev/null
	[ "$?" != "0" ] && $BREW install --cask ${CASK}
done