I wouldn't even bother with an Arduino/microcontroller at all for this. Just some diodes on each circuit and maybe some transistors for powering the large LED strips, or could also use tiny relays.
But I don't see where it has anything nearly complicated enough to have code running on a chip to run anything on it. @itjobhunter if this is not helpful and you need more specific details and/or a quick napkin sketch I can throw something together to show what I'm trying to say.
The motion sensor is used to turn on the lights in the garage via a Sonoff mini.
Also, I've had the garage door randomly open by itself (power glitches?) a few times over the years. So I'm adding an automation to close the door if no motion is present and it is after midnight.
I, too, am a "gray hair" (if I had hair). I despise cloud dependent devices. The reasons are many. ISPs, despite what they say, are not reliable. ISPs are so close to be monopolies, that they act like them. Your ISP can, and will, prevent access to the cloud if they have a competing product.
The manufacturers of cloud dependent devices, sell your information and statistics on how you use the devices. This is how they make money. When one of these manufacturers goes out of business, the company that buys up the IP continues to sell that information and ceases the little support that one did get.
I might be getting a little paranoid here, but I'm pretty sure there is unrelated-to-function software (spyware) incorporated into many products. (In the late 90's, the company for which I worked resisted the temptation to do so, despite heavy pressure from marketing.) I call it "ET phone home" Maybe the software is innocuous enough, but it can be hijacked by bad actors.
There is another problem plaguing home automation and that is poorly designed and poorly documented (which leads to pathetically supported) hardware and software. More so the latter. FAQs and forums are afterthoughts of the slothful, but now it's all we have.
I agree with ProfRob and I would add "better documentation".
As a note, when I pull on my pants, I sit on my bed, start my pants onto my feet, roll back and pull both legs up at once
So, the answers are:
No audible alarm in the unit itself. Instead, it contacts you via either the phone app, by email, by texting, or by telephone if it detects a fault.
If a fault is detected, it guides you into finding out where it is. If you're not able to locate the fault yourself, then Ting says it will pay up to $1000 for an electrician to find the fault, perhaps depending on what fault it thinks it detects.
At the sensor level, it monitors house voltage in real time, and keeps track of the high and the low for each day. It says that can be relevant if the transformer feeding your house from the utility is near a failure point, in which case it can alert you to contact the utility. It also monitors high frequency activity on the electrical system, which is what it uses to detect arcing.
Honestly, I'm not expecting it will ever actually detect a meaningful problem, but who knows? It was free from my insurance company, and so I presume they did a due-diligence analysis and concluded that the risk reduction justified their cost of buying and distributing it to their customers. If nothing else, the power monitoring might be useful in logging brownouts and over-voltages on the mains: if a server or other device goes wonky, I guess I could see whether it correlates to a voltage fluctuation on the mains. If there is a home assistant interface for it, then perhaps I could log all the real-time data using that and use grafana to graph it. That might be interesting data to review if a fault were ever detected.