GE makes zwave motion sensor switches and dimmers. The motion sensor can be decoupled from the switch/dimmer to provide only sensor alerts. These detect really well for me, and for 50$ you also get a smart switch or dimmer. Also, power requirements are fully taken care of.
https://www.amazon.com/GE-Occupancy-Required-SmartThings-26931/dp/B07226MG2T/