alt Hacker NewsIt really depends on the environment: wall materials, interference, signal strength, and even temperature and humidity all play a role. Honestly, 100 m² is probably too large for a single sensor to cover reliably.
That said, ESP32 boards are very inexpensive, you can find them online for around €1 or even less.
Is the ESP-S3 your recommendation? Or should one look into the ESP-C6 / another model? The prices I'm seeing here in Sweden are more around €10 rather than €1, but I guess that's still much less than the average presence detector.