

Oh, many years ago I had a baby monitor that included a pressure mat. If it detected no movement for a while (it was sensitive enough to detect breathing) it set off an alarm.
Although if such a thing exists today, it probably requires an app and a subscription. Enshitification.
And there’s are those gadgets that have a USB-C socket but don’t have the correct circuitry, so that they only work with a USB-A to C cable.