Not a particularly new device, but I recentely stumbled across these BLE mmW+PIR sensors when looking for a lower cost option (and available for that matter) battery powered mmW presence sensor.
These are BLE, so they are not suitable for anyone that doesn't also run Home Assistant and HADB. However if you do, these are inexpensive ($25 CAD or $18 USD), small and work extremely well, with zero lag. They are also IPX5 rated, so are perfect for use in bathrooms. Their claimed battery life is 2.5 years on a single CR2450 (included).
I'm using mine with a Xiaomi Mulitmode Gateway that I already had available, but Home Assistant also has a Xiaomi BLE integration and can support them directly as long as you have bluetooth capability on the computer hosting HA. I tested it connected directly to my RPi4 and it worked just as well as when connected via the Xiaomi gateway. There should be no reason you couldn't also use an ESP32 to extend the range if needed.
Works so well, I've already ordered more. Hope this is helpful to someone looking for a lower cost substitue for an Aqara FP300.
Included metal base for magnetically attaching to non-metalic surfaces.
Settings have to be adjusted from the app with your phone connected to the device via bluetooth. This does not disrupt the existing pairing, and you just need to push the button on the device to reconnect it to your phone and make the adjustments you want. You can then disconnect and the device will keep working via the gateway or direct connection to HA.
Time to reset can be as low as 3 seconds
