There are some factual errors in what you stated.
She isn't becoming the Secretary of State, but a high ranking official in the state department. Her role is to be a special envoy to discuss climate related topics with foreign states. Which absolutely makes sense as to stop climate change, an international effort needs to be made. The state department would be the obvious administration to conduct these talks and puts them on the same priority level as previously economical and military topics.
But indeed, she needs to take up a German passport to become a state official.
The actual secretary of state is from the Green party, Annalena Baerbock. She just deployed some great pragmatic & lateral thinking. They have an American lobbying as their official representative for their cause on the international stage and the US (obviously). And they export renewable tech to America. Win win. Move the cause further while doing some business.
I wouldn't necessarily have voted for the green party in Germany (I live here but I am not a German national), but this is both very rational and very smart. Loving it.
