ou have something like Pi 3 and if so why ? and what OS on it ?
If you want to buy one which one interests you.
Raspberry Pi3 for thermostat and Arduino for door automation.
Why I am getting the vibe here that it is easier to code and automate with Arduino , is there an easy guide/wizard for it that does not involve alot of coding ?
Arduino is microprocessor coded with a specific dialect of c as most of micros todays. It is not able to run an os. Like any micro it accepts an entry point and starts looping the same code again and again until you pull the plug.
Raspberrypi is an arm architecture able to run an os. You can code it even in python or node.js
I'm thinking about one of these for the kids' bedroom back in Texas so that we can have a multimedia and multipurpose device that we can hook up to a TV monitor but get more general purpose use out of it than we would with just a Fire Stick or something like that.
That's true. Don't know if they can afford to keep that up these days, though.
My first guess from how the design looks is that the processor board will be cheap, and that board that has the M.2 slot, USB3, video connector (couldn't see it), etc will be more expensive than it should be.