Hanovers, not Windsors. Let’s not be trans about it. You can’t pretend to be a different sex, or pretend not to be German.
"In 1917, the name of the British royal house was changed from the German Saxe-Coburg and Gotha to the English Windsor because of anti-German sentiment in the United Kingdom during the First World War."
https://yourwiseanswers.com/why-did-the-british-royal-family-changed-their-name-in-1917/
Actually, Battenburg.
The late Queen was half Scot, the present King has English, Scottish, Danish, Russian and some German ancestry.
The present King’s most recent ancestor born in Germany was HRH The Prince Consort, Queen Victoria’s husband, who left Saxe-Coburg-Gotha in 1840.
Given logic of your argument, and the rate of German immigration to the US, you would have to argue that 50 million Americans are really Germans not Americans.
In other words, it’s a dumb argument.