@sn0w I had a chuckle at this. Then I realised it wasn't a joke.
Haha. It isn't *that* complicated tbh.
The actual hot path to turn on the light on is two services and a redis server to act as the messaging queue.
The other part of that diagram is analytics (i.e. how they make money off you).
That said, it could all be replaced with one Home Assistant server running locally.