Andy Burns wrote:

There do seem to be PIR sensors that have been modified to be radar sensors

Probably your easiest retrofit is lamps with radar built-in, though the
end-firing lamps might not work best with a bulkhead style shade, also
I'd worry about the lifetime of cheap chinese LEDs being enclosed and
getting hot.

https://aliexpress.com/item/B22-5W-LED-Radar-Motion-Sensor-Lamp/32957832056.html