Running AI is so expensive that Amazon will probably charge you to use Alexa in future, says outgoing exec::In an interview with Bloomberg, Dave Limp said that he “absolutely” believes that Amazon will soon start charging a subscription fee for Alexa
That is not necessarily true. Some base stations use the internet, yes, but not all. For example a Philips hue does not require internet access, nor does Lutron Caseta. As the other person posted, Home Assistant is the absolute best (IMO) way to do everything locally without the internet.
Your system, while it might work for you, does not scale well due to the limited range and reliability of Bluetooth. You’d likely be better off to adopt a more robust protocol like Z-wave, or ZigBee and get a hub that you have full control over.