Will OS check if such python lib is installed or script running in the background? Then those that doing ad fraud will move to programmable board as BLE keyboard/mouse/hid. Even microbit can can be programmed as BLE HID device [1]. Add external camera on unattested device that will stare at attested device screen and you can automate lots of thing. Sure this is more complicated to pull off but will probably eventually happen anyway if this is a lucrative business.
In the end WEI wouldn't prevent ad fraud / fakes but would end up used for restricting other things.