Welcome to the community. You are starting right by reading through many of the threads here. My recommendation is start small with what you know and go system by system to make any determination if it should be automated and by what control point.
For example my security and thermostats are mission critical and they self supporting no matter what happens to my Hubitat or the internet, my house will heated and the alarm will continue to function. And both of these are secured by physical access to the property and the native applications from the vendors and only provide status to the Hubitat.
Lighting and other functions are managed via the Hubitat and have no internet dependency to continue to run for basic functionality. So it's good to think in layers of operating when implementing these functions.
Have fun with your journey also, if it starts to become a second job it may have gone too far.