I have good success with a cheap Tuya Humidity sensor I got off ebay a year ago. It took some time creating a custom driver last year, but it appears the built-in drivers have been modified/updated and now support the device fully. There's even a nice battery gauge on the display.
The battery has lasted about a year, and updates every so often (more than sufficient for my needs).
The only hitch/con is the on-device temperature display is clearly a non-US device with Celsius only, but the hubitat driver does conversion to Fahrenheit automatically for dashboards and rules.
here's the device which easily purchasable on ebay. Just search "Tuya Zigbee Humidity".
Zigbee Temperature And Humidity Sensor | Temperature and Humidity Sensor | Tuya Expo
