To the level that Hitler reportedly cried when he abdicated. While that is likely just a story, it does illustrate how much of a sympathizer he was. During the war he was shipped to the Caribbean to prevent him from being able to access anything sensitive.
And for Lindbergh, there is a famous Suess cartoon from his political comic days showing Charles as one half of the 'Siamese beard' and a certain German house painter as the other half. His sympathies were well known at the time.