If I remember correctly, there was a stream in the EU cacophony to get a common agreement for all ELA1 EASA-reg aircraft to be allowed to carry PLB only in all of Europe, but I admit, I did not follow up whether it was ever passed.
When I was renting aircraft all over Europe, I got almost nuts on the crackbrained spectrum of regulations related to the issue and ended in buying a mobile ELT. Luckily a mobile ELT can be registered to person in the UK register, don't ask what you encounter when asking this in some other countries ...