A P1 sensor. I have recently entered the rabbit hole of home automation. One of the things I care about, is to be as private as possible, so I went for Home Assistant.
A P1 sensor is a small thingumabob that you plug into your electricity meter and it measures electricity and natural gas use. It comes with its own webserver and it integrates seamlessly into my HA energy dashboard. I did not have to subscribe to any cloud service and as far as I can tell, it does not phone home.
What is your definition of stability? I have used Arch for about ten years without any major breakage, but sometimes you do have to do some manual tinkering if a package stops working. So it's stable enough for me, but maybe not for others. Since it is a rolling release, packages are generally being updated quite rapidly.
I think that any modern rolling release distro would fit the bill though.