See here below link. Reasonably cheap and promises a 1 year battery life.
- NEO Wifi Motion Sensor Alarm Detector PIR Motion Dectector For Smart Home Automation -
[https://ae01.alicdn.com/kf/HTB1IoSmdjfguuRjy1zeq6z0KFXaY.jpg?width=800&height=800&hash=1600]
Anyone tried? Says that it is Tuya compatible and, as I understand it, in current builds of HA these devices are autodetected.