1) Anything that obstructs the clear reading of a numberplate is illegal, including lighting that claims to "wash out" the numbers.
2) The vehicle numberplate light must conform to the Road Vehicles Construction and Use regulations which apply throughout the EU and UK.
3) Road vehicle numberplates must be manufactured to the correct BS standards by approved and licensed manufacturers to prevent non-reflective,"obscured", or incorrect font plates being fitted.
4) You would be stopped by the first police car that followed you because they have ANPR cameras and will immediately see that you have a device which is trying to obscure the numbers.
5) It will fail an MOT because the numberplate light is incorrect.
6) These light things don't work anyway to prevent ANPR camers reading the numberplate.
So you will be spending a lot of money and effort on a useless device which will get you fined, gain points and probably have your car impounded on the spot as "unroadworthy" untill you replace the lights.
You must never assume that American law-dodging products are useful or legal or even work at all.