Ref Holland and ELT..
I read on another forum that as Holland would need to file a difference to EASA
NCO.IDE.A.170 Emergency locator transmitter (ELT) requirements.
Which they have not yet done.
Then they cannot stop you from have an PLB over an ELT.
A state can file a difference from ICAO SARPs. It cannot "file a difference" from an EU regulation. A state that persists in applying different regulation will eventually find itself the subject of infringement proceedings by the Commission.