The ENS210 is a Relative Humidity and Temperature sensor with I2C interface.
Here you find documentation (appnotes, quickstart, user guide) and example sources for an ENS210 driver. For the datasheet please see the product page.
The hardware can be ordered.
There are two sets of drivers available for the ENS210. Both come as c source file with documentation and sample application using the driver.
There is a Linux driver (for the input subsystem), and a driver for small systems without and OS.