Send individual bluetooth LE packet from command line

I have a Bluetooth-controlled 'Smart Plug' to control appliances. I want to be able to control it using programs of my own devising, rather than just the manufacturer's proprietary app. I know how to pair form the command line using bluetoothctl , and have already gotten as far as using Wireshark to identify the packets being sent received when I switch the plug on or off in the app. Now, all I need is a way to actually send the LE packets/requests from the command line (I did not anticipate that this was where I would get stuck...). I have no previous experience developing with Bluetooth, but

Question by Drubbels on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.