So my question is that does the box work same way in both countries, I assume it should but yesterday retailworker from electronics shop said that they are not very common here (Finland) and only few might work, if you buy Amazon they won’t work. That doesn’t seem right but I don’t know for sure.

Second country is Catalunuya (Spain) and for example if I buy basic Xiaomi or 50-100€ box it should work just fine?

And less importantly, how about the service? Obviously I cal always change when I go from country to country but are they country based or ”everyone can use everything, it’s internet” ?