A cheap ESP32 and capacitive moisture sensor that logs soil conditions to a self-hosted dashboard and sends push alerts when your plants need watering.
A $4 ESP32 board that passively scans for your phone via Bluetooth and publishes room occupancy to a local MQTT broker — no cloud, no camera, no app.
A sub-$40 ESP32 sensor kit paired with a self-hosted web dashboard to track CO2, particulates, and VOCs in your home — no cloud account required.