I'm in Poland. When I had fiber installed I asked the provider if they could install an ONT. They balked a bit but eventually relented. They provided their own ONT at no extra cost. Orange is the provider, in case anyone is interested.

It's up to the discretion of the installer. I think being able to speak in technical terms and provide a decent argument convinced the installer. I got a feeling that they don't generally do it because for most people, the Orange FunBox is a good enough solution.