You can certainly measure the impact of EMF blocking devices using an EMF meter. For example, if you cover your smart meter with a Faraday cage, you should see significantly lower EMF readings as a result. However, you won’t be able to measure the impact of devices such as Lifetune because they don’t block EMFs. Instead, they change the structure of the radiation to be more in line with naturally-occurring EMFs. To measure their impact you’d need to use encephalography.