Ok, he's not a household name. Generally, you can say five things about Grenell:
1. He's a Republican (I know....that will worry most Germans....it's very frightful).
2. Highly educated (Master's degree in Public Administration from Harvard University's John F. Kennedy School of Government, with a bachelor's degree in Government and Public Administration from Evangel University (private Christian college in Missouri)). This should also worry Germans because he's had been educated via Christian college, and fairly intellectual.
3. He spent roughly eight years at the UN, as the US's chief spokesperson (throughout the Bush period). He can probably get all chatty and go on for hours about crisis X, Y and Z.
4. He's been on Fox News a good bit and can talk at length about worldly affairs. This would usually worry Germans.
5. He's openly gay. Yeah, a shocker for Germans....you can be gay, intellectual, and Republican.
How this will go over?
I'm guessing that the confirmation process will take three months (summer vacation period).....so he won't show up until early November. I'm also guessing that he will be invited onto one or two German public-chat-forum shows, and be asked over and over how a gay or intellectual can be a Republican. At some point, the stupidity of the German view will shine through to the general public, and everyone will have a good laugh that they were amused by the whole gimmick of biased news for months.
Grenell? He might actually be around for more than two or three years. It wouldn't surprise me if he's still there as ambassador in 2024. I suspect if you were looking for a badger-like instrument to dig claws into some biased news gimmick, and not let go....Grenell is probably that instrument.