> If everyone under the age of 30 was using an app run by Nazi Germany would you be okay with that?

First answer: I would ask myself why people are using a nazi-made app, first.

OTOH: the history of nazism in the US is more complicated than you think

A glimpse of it is summarized in the wikipedia page about it

https://en.wikipedia.org/wiki/Nazism_in_the_Americas

After all the US arrived first to the Moon thanks to "operation paperclip" and a a former nazi scientist.