I do it using MMWave sensor, 60Ghz one. Want to have more of them but installation is a pain as these need to be mounted on ceiling so WiFi based sensor would be awesome!
Unfortunately no. But fortunately, it isn't something new I have built. I use a Seed Studio sensor MR60BHA2 which has an ESP32 which sends the data to Home Assistant through ESPHome. Once it is in Home Assistant you can do automations and notifications. I mostly use it for elderly care. I have another DFRobot C1001 sensor but waiting for ESPHome to add support for it. It has fall detection also which is why I am planning to replace it. They are fairly accurate; ~90%; has been my experience. They work better when mounted on ceiling and have a cone like coverage.
don't get the $5 ones, they are probably just presence detector or at best distance detector and probably work on 24Ghz. Get the 60Ghz for breathing, heart rate, posture etc.
Infineon 60GHz IoT FMCW radar modules have all datasheets published. That's super rare for Infineon - usually they are the worst NDA-hell on earth.
Chinese vendors sell uC+Radar-Module units on Aliexpress for around ~20-30€. They Infineon-based boards are super easy to spot by looking at the Antenna-on-Chip layout.
You can cut off their head (microcontroller) and directly attach your favorite uC onto the SPI bus to talk to them. Or use the existing one.. not overly complicated to reverse engineer the schematic.
