If you want to say “it has this specific vegetable and that makes difference” then that’s another perspective I don’t agree with.

That’s not a point I’m trying to make. Although my idea of Döner Kebap includes specific vegetable/salad ingredients, to my understanding the defining step was putting it in a portable loaf of bread, instead of having kebap on a plate. And as another commenter said, that idea might have been re-imported. But neither was I around when it first appeared, nor am I a Döner Historian of any capicity, so I have to rely on the sources I read. I’m also not passionate enough about the topic to do a lot more research. But no matter it’s origins: Döner holds a very special place in Germany’s culinary environment and that’s thanks to Turkish immigration history. So it’s definitely a significant food in this country.

Nobody denies its Turkish roots though. AFAIK putting Kebap in bread isn’t really a thing in Turkey and although one might argue how big a contribution that is, it’s that step that combined a Turkish dish with German Imbiss culture and made this a huge success all over Germany.

You’re welcome to try the same thing with Schnitzel and if you attain the same level of success and cultural significance, I’d rightfully call you the “inventor”. (though I have to inform you, that “Schnitzelsemmel” is a thing already, so maybe think of a different example)