This is script to auto on/off a Logitech light when the webcam is on/off in Mac. It requires hidapitester. Modified to support multiple lights.

litra-auto-on.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
   <key>Label</key>
   <string>litra-auto-on</string>
   <key>ProgramArguments</key>
   <array><string>/Library/LaunchDaemons/litra-auto-on.sh</string></array>
   <key>RunAtLoad</key>
   <true/>
</dict>
</plist>

litra-auto-on.sh

#! /bin/bash

# Download both files and https://github.com/todbot/hidapitester to /Library/LaunchDaemons/
# Execute the following commands to launch it on login
# sudo chown root:wheel /Library/LaunchDaemons/litra-auto-on.plist
# sudo chmod 600 /Library/LaunchDaemons/litra-auto-on.plist
# sudo launchctl load -w /Library/LaunchDaemons/litra-auto-on.plist
# sudo chmod 0744 /Library/LaunchDaemons/litra-auto-on.sh 
# sudo chown root:wheel /Library/LaunchDaemons/litra-auto-on.sh 
# sudo launchctl bootstrap system /Library/LaunchDaemons/litra-auto-on.plist
# For test it:
# launchctl start litra-auto-on
# For logs add to the plist:
# <key>StandardErrorPath</key>
# <string>/tmp/litra.auto.err</string>
# <key>StandardOutPath</key>
# <string>/tmp/litra.auto.out</string>


# Use 046D/C900 for older models
model="046D/C900"
# serial numbers for multiple lights
serial01="SERIALONE"
serial02="SERIALTWO"
# Change to your own path
hidapitester="/Library/LaunchDaemons/hidapitester"

on="0x11,0xff,0x04,0x1c,0x01"
off="0x11,0xff,0x04,0x1c"

log stream --predicate 'subsystem contains "com.apple.UVCExtension" and composedMessage contains "Post PowerLog"' | while read LOGLINE; do
	if [[ "${LOGLINE}" == *"On;"* ]]; then
		eval "$hidapitester --serial $serial01 --open --length 20 --send-output $on"
		eval "$hidapitester --serial $serial02 --open --length 20 --send-output $on"
	elif [[ "${LOGLINE}" == *"Off;"* ]]; then
		eval "$hidapitester --serial $serial01 --open --length 20 --send-output $off"
		eval "$hidapitester --serial $serial02 --open --length 20 --send-output $off"
	fi
done