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I recently learned about Home Assistant here on Lemmy. It looks like a replacement for Google Home, etc. However, it requires an entire hardware installation. Proprietary products just use a simple app to manage and control devices, so can someone explain why a pretty robust dedicated device is necessary as a replacement? The base model has a quad core processor, 4 gigs of ram, and a 32 gig hard drive. Admittedly it's no gaming PC, but it's no arduino either.

What actually happens when I turn on a smart switch in my home? Does that command have to be sent to a server somewhere to be processed? What really has to be processed, and why can't a smartphone app do it?

Edit: I am still getting new replies to this (which are appreciated!), but I wanted to share what I've learned from those who have posted already. I fundamentally misunderstood how smart switches work. I had very wrongly assumed that when my phone is connected to the WiFi, it sends a signal over the local network to toggle the switch, which is connected to the same network, and it turns on/off. While there are technologies that work like this (zigbee, kinda?), most smart home devices rely on a cloud server to communicate the signal. This enables features like using the switches from outside the home network, automation, voice controls, etc. The remote server is what's being replaced.