I would also suggest to just try using tags. It’s easy and it means you don’t have to make a flow for every device:
Battery level low:
https://homey.app/nl-nl/flow/q3CUVD/
Temperature devices not reporting
https://homey.app/nl-nl/flow/jtGVVD/
You can also remove the condition and receive a notification for every device that’s not working, I only needed the temperature sensors.
