I have a Dell Chromebook that's been running (Debian) without issue (battery removed) in a similar capacity for over a decade, and four more that have been up for the last five years. The former I bought new, the latter are all second-hand survivors from some public school program. They're solid.

My personal preferred infra there would be for all devices to be meshed together, and a smart water shutoff valve able to cut off automatically if a water leak sensor trips.

I installed a water siphon backup for the sump pump. It creates a water siphon if the level gets above the electric sump and drains the pit. Is basic plumbing to install. Other than wasting a half gallon for every 20 gallons pumped out, it doesn't really on any technology nonsense.

It's better than nothing sitting between you and knowing your cellar is flooding, and I could think of worse solutions than a device with a built-in UPS that's capable of powering a sensor.

Do older Chromebooks not carry the spicy pillow risk MacBooks have when plugged in 24/7?

It’s not gonna be an internet response, but there are already water alarms. You’re typically meant to put them under your sink.

especially if you keep your Chromebook in the cellar ;)

but isn't the alternative to have some third party on the Internet sitting between you and knowing that your cellar is flooding? third party services in the cloud have downtimes (not necessarily less than your Chromebook), tend to shut down entirely over time, tend to give up on you if you're not on a premium plan, tend to stop supporting the version of your device, etc