I hear now there's an unofficial bridge (runs as a NodeJS service) called Homebridge which might get Harmony working with Siri, and Lutron has newer lights not using Z-Wave that are Homekit compatible, but when I was shopping for all this stuff several years ago Siri /HomeKit support was abysmal.

It also helps that Echo's microphones and speech recognition is much better at far distances, with background noise, than "Hey Siri" (and assuming I don't have my phone in my pocket). At this point, I pretty much only use Siri when I'm in the car, and that's the environment where it seems to perform the worst (long delays to start listening, frequent misunderstandings, request failures).