Renovating outdated smart home to AppleHomeKit

Im starting a job on a already "Smart Home" that has multiple hubs and a nightmare amount of apps built with a lot of old out dated tech. Im going to redo the whole house with everything Apple has to offer very basic and minimal automation capabilities. But to kick of the project we are starting with an alarm system that needs to send a notification to the home owner and trigger flood lights out side and potentially a few lights inside as well as sound off an alarm.

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