IKEA `PARASOLL` Door/window sensor

Occasionally the doors/windows of the house are left open (people forget to close them) overnight ... 😬
It hasn't been an issue _yet_, but the low crime rate in `Braga` isn't something we can rely on forever ... ⏳
So I'm considering getting door/window open sensors to test.

https://www.ikea.com/pt/en/p/parasoll-door-window-sensor-smart-white-80504308/

This is a basic reed switch with low power coms powered by `AAA` batteries, exactly what we need.
Given the low cost - **`€9.99`** at the time of writing - thinking of getting two to start.
We have a _lot_ of windows in this house so getting one of these for each of them might get expensive ...
But for security/safety reasons, we only need to cover the _bottom_ floor which has windows/doors
that humans can enter/exit ...