Something simple? You approach seems to be simple, not mine. Can you use that system as a security alarm and send push notifications to your phone? My system can. There are different approaches, don't underestimate others different than yours.
Yes, you can. https://github.com/witnessmenow/push-notifications-arduino-e...
Someone can do everything you mentioned on a cheaper, smaller device; one that’s not running an entire OS that has to be maintained.