Hi Philipp Jonathan,
Have you tried DNA testing? Maybe that would help with your questions. I don’t know that much about it, but maybe others will chime in.
I find your empathy moving and to your credit, although it is hard for me to understand how people cannot have that reaction—i.e., the current anti-semites, neo-Nazis, and Holocaust deniers. I am Jewish and have spent periods of my life thinking about the Shoah every day, too. It is just so hard to comprehend that something so terrible and so immense could be done by supposed human beings. Anything else I say will seem trite and others have expressed it better—I can barely think of words for this. I am named for my grandmother’s sister, Leah Zabludowicz, z”l, murdered by the Nazi beasts in 1942. I am currently listening to testimony by one of her sons. So yes, I think about it every day, and try to remember the people who were tortured or murdered—read about them, remember their names, wonder about them as real people, imagine the communities before the war, and never forget. And I was not a survivor—one who has the actual memories tormenting them.
Whether you have Jewish ancestry or not, you sound like a mensch. And that is what is really important. And you certainly do have a complicated background and identity—be proud of who you are.
May you have good luck in your searching, and peace no matter what you find.