Getting started with the Samsung Smart Home setup is fairly cheap if you buy a package like this one. Since the hub itself is about $70, and sensors are $20-40 each, getting the hub and multiple sensors for $100 is a good deal.
https://www.crutchfield.com/p_305MONKIT1/Samsung-SmartThings-Home-Monitoring-Kit.html .
The hub connects to your router, and then you can use a free phone app to access the hub and get the status of the sensors.
The smaller package I bought a few months ago had the hub, a water sensor, and a door/window sensor. Both sensors also read temperature, so I put the water sensor next to my water heater/boiler to detect water and show the temp near the boiler, and put the window sensor on the main floor to read the temperature near the thermostat.
You can set an acceptable range for the temperature, and then when you check the app it just displays a big "OK" to tell you the temperature is within range. If you click on a specific sensor icon it shows you the exact temp, and for the water sensor it shows "Dry."
Samsung Hub can also work with z-wave and zigbee devices, but I have not tried to use any.
Bruce