What do you guys think of the idea of smart homes? I could make a basic setup using https://home-assistant.io to control my home temperature and lighting; the tools for doing this are everywhere nowadays and implementation doesn't seem too horrific anymore.
But setting aside what I "can" do, is this something that I "should" do? How can a person implement this without connecting any devices to the internet?
It's a great and rewarding hobby! But having cloud connected devices on the same devices as your sensitive information is an issue.
Use a vLAN and IoT devices capable of local control. Use a self hosted hub like Home Assistant. Keep devices that collect sensitive information (like a camera) out of sensitive areas (like the bedroom). Then you should be reasonably secure.